The study, published in Case Studies in Chemical and Environmental Engineering, tackles a stubborn chemical problem. Coffee parchment is packed with cellulose, around 54 percent by weight in the Ethiopian samples tested, but it is also loaded with lignin, the tough aromatic polymer that glues plant cell walls together. Lignin forms strong lignin-carbohydrate complexes that shield the cellulose and resist conventional processing. Ordinary alkaline treatment with sodium hydroxide can strip away some of this lignin, but it demands long reaction times and heavy chemical doses, and even then it leaves behind stubborn residues that discolor and weaken the final product.

The researchers’ solution was to bombard the biomass with high-intensity ultrasound while it soaked in the alkaline solution. When an ultrasonic probe submerged in a liquid operates, it generates cavitation: the rapid birth, growth and violent collapse of microscopic bubbles. Each collapse releases a burst of localized energy, producing microjets and shear forces that erode particle surfaces, break open cell walls and dramatically improve the penetration of chemicals into the fibrous matrix. Crucially, the acoustic energy also cleaves the chemical bonds linking lignin to carbohydrates through homolysis, freeing the lignin for dissolution.

The numbers are striking. Conventional treatment with 4 percent sodium hydroxide at 90 degrees Celsius for four hours removed only about 29 percent of the lignin. When the same alkaline solution was assisted by 60 minutes of sonication, delignification climbed to roughly 50 percent, and the cellulose content of the treated material rose from 54.3 percent to 71.8 percent, while preserving 96.3 percent of the original cellulose. Notably, a milder 4 percent alkali dose with ultrasound outperformed a stronger 8 percent dose without it in terms of cellulose recovery, meaning less chemical consumption for comparable or better results.

But delignification alone was not enough to unlock the pure white cellulose the team was after. The pretreated fibers still carried residual lignin locked within insoluble complexes, so the researchers applied a two-stage bleaching sequence targeting different lignin substructures under complementary pH conditions. The first stage used alkaline hydrogen peroxide, stabilized with sodium silicate and Epsom salt, which generates hydroxyl radicals that attack nonphenolic lignin structures. The second stage employed sodium chlorite buffered in acetic acid at pH 4.5, the classic Wise method, in which chlorite oxidatively opens the aromatic rings of lignin, converting them into water-soluble acidic fragments that simply wash away.

The contrast between the two processing routes was dramatic. The conventional route, without ultrasound, reached an overall delignification of 72.5 percent after both bleaching stages, leaving the final material at 83.3 percent cellulose. The ultrasound-assisted route pushed delignification to 93 percent and delivered a final microfibrillated cellulose of 91.8 percent purity, with residual lignin slashed from an initial 25.5 percent down to just 3.5 percent. After three bleaching cycles, the fibers displayed the characteristic whiteness of purified cellulose, a visual proxy for its chemical purity.

A battery of analytical techniques confirmed the transformation. Scanning electron microscopy revealed raw parchment as a dense, rigid matrix of tightly packed fiber bundles, which yielded after the full treatment to discrete, elongated, ribbon-like fibrils roughly 10 to 12 micrometers wide. The ultrasound route produced slightly thinner and more fragmented fibrils, evidence that acoustic cavitation disrupts the hydrogen-bonded interfaces between microfibrils. Infrared spectroscopy showed the disappearance of peaks associated with lignin and hemicellulose, while X-ray diffraction confirmed that the cellulose crystal structure, of the cellulose I type, remained intact throughout.

Perhaps most impressive was the gain in crystallinity and thermal stability. The crystallinity index, a measure of the ordered crystalline fraction of the material, rose from 60.4 percent in raw parchment to 80.8 percent in the final product, as amorphous lignin and hemicellulose were stripped away. Thermogravimetric analysis showed that the purified cellulose resisted decomposition up to 264 degrees Celsius, with peak degradation at 367 degrees, well above the raw material, and left only 4 percent char residue compared with over 25 percent for untreated parchment. These properties matter because thermally stable, highly crystalline cellulose can survive the high processing temperatures of polymer compounding, making it suitable as reinforcing filler in plastics and biopolymers.

Particle measurements added a further endorsement. Suspensions of the ultrasound-derived cellulose showed smaller apparent hydrodynamic diameters, about 1,623 nanometers versus 2,367 nanometers for the conventional route, and zeta potentials of minus 37 millivolts, comfortably beyond the threshold for colloidal stability. In plain terms, the fibers disperse well in water without clumping, a property essential for forming uniform films, coatings and composite materials.

The authors are careful to note the caveats. The process still requires substantial energy and chemical inputs, including multiple bleaching cycles, extensive washing, oven drying and freeze-drying, and its environmental and economic advantages cannot be confirmed without full life-cycle and techno-economic analysis. Scaling ultrasound systems from laboratory flasks to industrial batch or continuous operation remains a significant engineering challenge. Even so, the study demonstrates a credible pathway for turning a burned waste product into a material of growing commercial importance, and future work on surface modification could broaden its use in advanced sustainable materials. For a country whose coffee sector discards thousands of tonnes of parchment each year, the idea that sound waves could help convert that waste into high-value cellulose is a compelling glimpse of the circular bioeconomy in action.

Subject of Research: Ultrasound-assisted isolation of microfibrillated cellulose from Ethiopian coffee parchment waste

Article Title: Impact of combined ultrasound-assisted alkaline delignification and two-stage bleaching for efficient microfibrillated cellulose isolation from Ethiopian coffee parchment

Article References: Kidanu, B. T., Sibhatu, A. K., & Tizazu, B. Z. (2026). Impact of combined ultrasound-assisted alkaline delignification and two-stage bleaching for efficient microfibrillated cellulose isolation from Ethiopian coffee parchment. Case Studies in Chemical and Environmental Engineering, 14, Article 101504. https://doi.org/10.1016/j.cscee.2026.101504

Image Credits: AI Generated

DOI: 10.1016/j.cscee.2026.101504

Keywords: coffee parchment, microfibrillated cellulose, ultrasound, delignification, bleaching, biomass valorization, Ethiopia, lignocellulose, crystallinity, biorefinery, Impact, combined

The central challenge addressed by the team concerns non-fullerene acceptors, or NFAs, the electron-accepting molecules that have driven the recent surge in organic photovoltaic performance. In a bulk heterojunction solar cell, a donor polymer and an acceptor molecule are blended together to form an interpenetrating network through which photogenerated charges must travel. For efficient charge generation and transport, the acceptor molecules need to pack into ordered, crystalline domains with close π-π stacking, the parallel overlap of their conjugated π-electron systems that facilitates electron delocalization. Yet excessive crystallinity can cause the acceptor to separate from the donor polymer, degrading the miscibility of the blend and producing a coarse, unstable morphology. Historically, molecular designs that pushed crystallinity upward tended to sacrifice blend compatibility, and designs that preserved compatibility tended to leave behind disordered packing and large nonradiative energy losses, the fraction of absorbed photon energy dissipated as heat rather than converted into charge.

The SUSTech group, led by corresponding author Professor Feng He, approached this dilemma through what the researchers describe as fine molecular engineering. Rather than redesigning the acceptor scaffold wholesale, the team made selective, targeted modifications to a parent molecule designated 7C-2F, which is built around a 1,4-diazahexane core. From this starting point, three new non-fullerene acceptors were synthesized by independently controlling two structural variables: the length of the side chains attached to the molecular framework and the degree of π-conjugation in the terminal groups, the electron-deficient end units that largely govern the optical and electronic properties of the acceptor. This modular approach allowed the researchers to isolate the effect of each structural change on molecular packing, blend morphology, and device behavior.

The first structural variable, side chain shortening, produced two acceptors named 7C-BO-2F and 7C-eC9-2F. The second variable, extension of the π-conjugation of the terminal groups, produced a third acceptor named 7C-N2F. Although these two strategies act on different parts of the molecule, the study found that both converge on the same set of physical outcomes. Each modification improved molecular crystallinity, meaning the acceptor molecules adopted more ordered solid-state packing, and each shortened the π-π stacking distance, the spacing between adjacent conjugated planes in the crystalline domains. Closer stacking strengthens electronic coupling between molecules, which promotes efficient charge transport. Critically, the enhanced order also suppressed nonradiative energy loss, the dominant remaining channel through which modern organic solar cells squander potential voltage.

The photovoltaic results underscore how consequential these fine structural adjustments proved to be. When the acceptor 7C-eC9-2F was paired with the donor polymer PM6 in a conventional bulk heterojunction device, the system achieved a power conversion efficiency of 19.67 percent, a figure that places it among the highest-performing organic photovoltaic systems reported. Equally significant is the energy loss of only 0.539 electron volts, a remarkably small value for an organic solar cell. Nonradiative losses arise when excited molecular states decay without emitting photons or generating charges, and suppressing them is widely regarded as the principal route to raising the efficiency ceiling of organic photovoltaics. The fact that the same molecular features that tighten crystalline packing also curtail these losses illustrates the internal coherence of the design strategy: efficiency gains and morphological improvements flow from a single, unified structural logic rather than from competing optimizations.

Stability, the perennial weak point of organic solar cells, is where the new acceptors distinguish themselves most decisively. Devices based on 7C-eC9-2F were subjected to two standard accelerated aging tests. Under continuous illumination, the time required for the device efficiency to fall to 80 percent of its initial value, a benchmark denoted T80, reached 2728 hours. When the devices were held at 65 degrees Celsius, a temperature representative of real-world rooftop operating conditions, the T80 value reached 1242 hours. In both tests, the 7C-eC9-2F devices significantly outperformed the control systems included in the study. The researchers attribute this durability to the optimized molecular aggregation states and the clear, well-defined microstructure of the active layer, which maintains its charge-generating and charge-transporting architecture even under sustained thermal and optical stress. In effect, the same crystallinity that boosts efficiency also anchors the morphology against the gradual coarsening that typically degrades organic photovoltaic devices over time.

The improved performance stems from a convergence of factors that the authors identify as the mechanistic foundation of the work. Sophisticated molecular engineering of the acceptors produced optimized aggregation states, improved crystallinity, suppressed nonradiative recombination, and a well-defined microstructure. These properties collectively promote efficient charge generation and transport while ensuring morphological durability. The balance between crystallinity and miscibility, often treated as an unavoidable compromise in acceptor design, is here resolved by structural tailoring so precise that both properties improve together. The side chain and terminal group modifications act on the molecular fine structure in ways that tighten packing within acceptor domains without provoking the macroscopic phase separation that would destroy blend compatibility, a result the researchers link directly to the simultaneous gains in efficiency and stability.

Beyond the bulk heterojunction architecture, the team also evaluated the new acceptors in quasi-planar heterojunction, or Q-PHJ, devices, an alternative fabrication geometry in which the donor and acceptor layers are deposited in a more layered arrangement rather than as a fully intermixed blend. The acceptors delivered excellent photovoltaic performance in this structure as well, demonstrating good fabrication adaptability. This cross-process applicability matters for practical manufacturing, because different deposition and annealing protocols impose different demands on material systems. An acceptor that performs well across multiple device architectures offers device engineers substantially more flexibility than one optimized for a single fabrication route, and the Q-PHJ results suggest that the benefits of the fine structural tailoring are intrinsic to the molecules themselves rather than dependent on any particular processing window.

The research was carried out by a team whose co-first authors are Dr. Mingpeng Li, Dr. Waqar Ali Memon, and postdoctoral fellow Xue Lai, all senior visiting scholars in the Department of Chemistry at SUSTech, with Professor Feng He serving as corresponding author. The work was supported by the National Natural Science Foundation of China and the Shenzhen Natural Science Foundation. The study was published on 11 September 2026 under the title Subtle Structural Tailoring Enables Improved Crystallinity and Miscibility for High-Efficiency, Stable Organic Photovoltaics, and the authors report no conflict of interest. The article is available as diamond open access, with no fees for authors or readers, consistent with the publishing model of CCS Chemistry.

The broader significance of the study lies in the design guidance it offers for the next generation of organic photovoltaic materials. By demonstrating that selective control of side chain length and terminal group conjugation can raise crystallinity, shorten π-π stacking distances, suppress nonradiative energy loss, and preserve blend miscibility all at once, the work provides a practical molecular blueprint for overcoming the efficiency-stability trade-off that has constrained the field. The performance of the PM6:7C-eC9-2F system, with its 19.67 percent efficiency, 0.539 electron volt energy loss, 2728-hour illumination T80, and 1242-hour thermal T80 at 65 degrees Celsius, constitutes a concrete benchmark for what fine molecular engineering can achieve. As organic photovoltaics move from laboratory curiosities toward commercial devices, strategies of this kind, which treat molecular fine structure as the primary lever for both efficiency and intrinsic stability, are likely to shape the material systems that carry the technology into practical deployment.

Subject of Research: Organic photovoltaic materials and molecular engineering

Article Title: Fine-structure regulation improves crystallinity and compatibility to achieve efficient and stable organic photovoltaics

Article References: Fine-structure regulation improves crystallinity and compatibility to achieve efficient and stable organic photovoltaics. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: organic photovoltaics, non-fullerene acceptors, molecular engineering, solar energy, CCS Chemistry, energy loss, device stability, bulk heterojunction, Fine-structure, regulation, improves, crystallinity

The significance of the result lies in what it replaces. Conventional COF synthesis typically demands days of heating under aggressive acid- or base-catalysed conditions, extensive screening of solvents and temperatures, and careful matching of reaction conditions to each monomer combination. Even then, many products emerge with imperfect crystallinity or compromised porosity, the two properties that make COFs valuable for gas separation, catalysis, energy storage and proton conduction. The new strategy, by contrast, produces imide-, imine-, hydrazone- and sp2-carbon-linked COFs within hours, with high crystallinity and porosity, using a catalyst that can be recovered and used again.

Benzimidazole occupies a special position among organic molecules because it is amphiprotic: it can donate a hydrogen bond through its N-H group and accept one through its pyridine-like nitrogen. That dual character is the engine of the new method. Unlike conventional acid or base catalysis, which activates monomers by proton transfer, the benzimidazole catalysts engage monomers, intermediates and transition states simultaneously through explicit hydrogen-bonding interactions, lowering the energy barrier at every step of the polymerization rather than at just one.

The authors demonstrate the approach most thoroughly on imide-linked COFs, a class prized for its chemical robustness and its applications in batteries, sensing and carbon capture. In the prototypical TAPB-PMDA-COF, formed from a triamine and a dianhydride, the catalyst accelerates the imidization reaction while promoting its reversibility, so that the growing network can continuously repair defects and settle into the thermodynamically favoured crystalline state. Powder X-ray diffraction profiles of the resulting materials show sharp reflections and narrow full widths at half maximum, hallmarks of long-range order that typically require days of solvothermal treatment to achieve.

Control is a second virtue of the method. Because the catalyst acts through noncovalent interactions rather than stoichiometric consumption, the reaction outcome can be tuned simply by varying the catalyst-to-monomer ratio. This knob allows the team to balance reaction rate against error correction: too little catalyst leaves the system slow and kinetically trapped, while the right proportion drives rapid bond formation and rapid bond exchange in parallel, the combination that crystalline polymer growth requires. The same logic extends across linkage chemistries, as the team showed by preparing the imine-linked TPB-DMTP-COF, the hydrazone-linked COF-43 and the sp2-carbon-conjugated sp2c-COF-16 under the same catalytic regime.

Theoretical calculations by Hongde Yu and Thomas Heine at the Technical University of Dresden, performed with density functional theory, support this mechanistic picture. The computations indicate that hydrogen-bonding interactions with the catalyst stabilize the transition states of the linkage-forming reactions and lower activation barriers for both the forward and reverse directions. Reversibility is the crucial ingredient: a network that can break and remake its bonds while it forms is one that can anneal itself into crystallinity, whereas an irreversible polymerization locks in disorder.

Scalability has long been the Achilles heel of COF chemistry, because many celebrated syntheses yield only tens or hundreds of milligrams after days of reaction. The hydrogen-bonding protocol supports a 1,000-fold scale-up, and the catalyst itself can be reused, addressing both the cost and the waste streams that would otherwise accompany industrial production. The scaled materials retain the high crystallinity and porosity of their small-batch counterparts, suggesting that the catalytic mechanism is robust to the heat- and mass-transfer realities of larger reactors.

The practical payoff is illustrated by proton conduction, a property central to fuel cells and electrolyzers. COFs prepared by the new route achieve benchmark proton conductivity, consistent with the team’s earlier work showing that crystalline porous frameworks can serve as exceptional proton-conducting electrolytes when their pores are engineered with appropriate carrier chemistry. Because the hydrogen-bonding synthesis delivers frameworks with well-defined channels and high surface areas, the resulting membranes combine the structural order needed for efficient transport with the mechanical and chemical stability demanded by devices.

The strategy also draws on a distinguished lineage in organic chemistry. Explicit hydrogen-bonding organocatalysis, pioneered for enantioselective reactions by chemists such as Peter Schreiner and Eric Jacobsen, relies on small-molecule donors that activate substrates without transferring protons. Applying that philosophy to polymer crystallization is conceptually elegant: the same interactions that guide a single reaction’s transition state can, when applied throughout a growing network, guide the entire system toward order. The result is a synthesis that is simultaneously faster, milder and more general than the harsh protocols it replaces.

For a field whose promise has often outrun its practicality, the message is striking. A cheap, recyclable heterocycle, acting through nothing more exotic than hydrogen bonds, can now build some of the most sophisticated materials in chemistry in hours instead of days, at gram scale instead of milligram scale, and with the crystalline quality that applications demand. If the approach proves as general across monomer families as the initial results suggest, hydrogen-bonding catalysis may become the default route to covalent organic frameworks, and the porous architectures built from it may finally move from the pages of review articles into the membranes, electrodes and catalysts of working technology.

Subject of Research: Hydrogen-bonding organocatalysis for the rapid, scalable synthesis of crystalline covalent organic frameworks

Article Title: Synthesis of covalent organic frameworks through hydrogen-bonding catalysis

Article References: Ye, X., Tao, S., Yu, H., Heine, T., Shao, H., Mu, X., Liu, Y., Xu, H., Lin, M., & Jiang, D. (2026). Synthesis of covalent organic frameworks through hydrogen-bonding catalysis. Nature Synthesis. https://doi.org/10.1038/s44160-026-01180-8

Image Credits: AI Generated

DOI: 10.1038/s44160-026-01180-8

Keywords: covalent organic frameworks, hydrogen-bonding catalysis, benzimidazole, organocatalysis, porous materials, imide-linked COFs, crystallinity, proton conduction, polymer synthesis, Nature Synthesis, scale-up, reversible polymerization

The material at the heart of the study is poly(vinylidene fluoride-trifluoroethylene), or P(VDF-TrFE), a ferroelectric copolymer that has long been a favorite of the flexible electronics community. Its appeal lies in the fluorine-rich backbone: each repeating unit carries a strong dipole moment, and when those dipoles are locked into the all-trans conformation known as the beta phase, the polymer becomes strongly piezoelectric. The catch is that achieving a high fraction of beta phase usually demands aggressive processing, such as electrospinning under high electric fields, stretching, poling at elevated temperatures, or the addition of inorganic fillers like barium titanate nanowires or zinc oxide. Each of those routes carries a cost, whether in manufacturing complexity, mechanical softness, or the brittleness that ceramic particles inevitably introduce into an otherwise compliant film.

The trade-off the researchers set out to solve is a familiar one in wearable electronics. Rigid piezoceramics such as lead zirconate titanate deliver enormous output but cannot conform to skin, joints, or curved automotive surfaces. Ferroelectric polymers bend beautifully but historically produce weaker signals. Composite approaches that sprinkle ceramic fillers into the polymer matrix recover some of the lost output, but they raise the modulus of the film, complicate fabrication, and can create stress concentrations that shorten device lifetime. An all-organic solution that raises piezoelectric performance without sacrificing flexibility would therefore be a genuinely useful addition to the toolkit, and that is precisely what the phytic acid strategy appears to deliver.

Phytic acid, a phosphorus-rich molecule found abundantly in plant seeds, is studded with phosphate groups that are eager hydrogen-bond donors and acceptors. When blended into P(VDF-TrFE), these groups interact with the fluorine atoms and the molecular environment of the copolymer chains, and the team reports that this interaction promotes both the formation of the beta-phase conformation and the oriented arrangement of the dipole moments within the crystalline regions. In effect, the small molecule acts as a molecular template: it nudges the polymer chains away from the energetically comfortable but piezoelectrically useless alpha phase and toward the extended, polar all-trans arrangement, while simultaneously improving the overall crystallinity of the film. Because the additive is organic, the resulting composite remains a fully polymer-based material with the compliance that wearable applications demand.

The doping level proved critical. The team systematically varied the phytic acid content and found that at 4 weight percent the composite reached its optimum, with beta-phase content peaking at 78.8 percent and beta-phase crystallinity at 38.69 percent. Below that loading, the hydrogen-bonding network is too sparse to reorganize a sufficient fraction of the chains; above it, excess small molecule presumably disrupts the packing of the polymer crystals themselves. This kind of volcano-shaped dependence is common in molecularly engineered ferroelectric polymers, and identifying the sweet spot is essential for any practical device, since both the piezoelectric output and the mechanical integrity of the film depend on getting the crystalline microstructure right.

With the optimized film in hand, the researchers fabricated a flexible piezoelectric pressure sensor and put it through a battery of tests. The device achieved a sensitivity of 45.87 millivolts per newton with a linearity of 0.97, meaning its electrical output tracks applied force with very little deviation across the measured range, a property that matters enormously for any sensor intended to quantify pressure rather than merely detect it. The temporal performance was equally impressive for a polymer-based device: a response time of 37 milliseconds and a recovery time of 53 milliseconds, fast enough to capture dynamic events such as impacts, pulses, and rapid finger taps in real time.

Perhaps the most reassuring result for anyone imagining commercial deployment is the fatigue behavior. Over 4,000 loading cycles, the output waveform of the sensor showed no attenuation and no distortion, indicating that the hydrogen-bond-enhanced crystalline structure is not a fragile artifact of processing but a robust feature of the material. Fatigue resistance has historically been a weak point for composite piezoelectrics, where interfacial debonding between filler and matrix gradually degrades performance. An all-organic system in which the enhancement mechanism is distributed at the molecular level avoids that failure mode entirely, which helps explain the clean, stable signal the team observed throughout the endurance test.

The broader context makes the result more than a laboratory curiosity. Flexible self-powered sensors based on piezoelectric, triboelectric, and pyroelectric effects have proliferated rapidly in recent years, finding roles in physiological monitoring, human-machine interfaces, motion capture, and structural health monitoring in demanding environments such as high-speed railway infrastructure, a field reflected in the study’s funding from the China Railway Group research program. Within that landscape, the PVDF family of polymers dominates because of its processability and strong intrinsic dipoles, and much of the current research effort, including work on grafting strategies, co-crystallization, molecular splints, and beta-phase programming, aims at exactly the same goal: raising the polar fraction of the polymer without compromising its mechanical character. The phytic acid approach adds a low-cost, scalable, and entirely organic entry to that list.

There are also practical advantages to the chemistry itself. Phytic acid is inexpensive, widely available, and derived from renewable biomass, in contrast to the specialized nanoparticles or fluorinated additives that many composite strategies require. The fabrication route involves straightforward blending of the additive into the copolymer, avoiding the dispersion challenges, agglomeration, and interfacial engineering that plague ceramic-filled systems. For manufacturers weighing the cost of producing conformal pressure sensors at scale, a one-step molecular modification that boosts the key figure of merit is an attractive proposition, particularly one that leaves the film’s flexibility untouched.

The study does leave open questions that future work will need to address, including how the composite performs under humidity and temperature extremes, whether the hydrogen-bond network remains stable over years rather than thousands of cycles, and how the sensitivity compares across a wider dynamic range of forces. But the core demonstration stands on its own: a hydrogen-bonding small molecule, used at a carefully tuned loading, can reorganize a ferroelectric copolymer into a highly polar, highly crystalline state and yield a flexible sensor that is sensitive, linear, fast, and durable. As wearable electronics, soft robotics, and embedded structural sensors continue their march from prototypes to products, molecular engineering of the polymer itself, rather than the bolting-on of ceramic reinforcements, looks increasingly like the path forward, and this work offers a compelling proof of concept.

Subject of Research: Hydrogen bond-induced enhancement of beta-phase content in all-organic P(VDF-TrFE) piezoelectric films for flexible pressure sensors

Article Title: Hydrogen bond-induced high β-phase piezoelectric films for high-performance flexible piezoelectric sensors

Article References: Liao, Y., Xu, Q., Zhang, Y., Guo, W., & Wu, J. (2026). Hydrogen bond-induced high β-phase piezoelectric films for high-performance flexible piezoelectric sensors. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13413-4

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13413-4

Keywords: piezoelectric, P(VDF-TrFE), phytic acid, hydrogen bonding, beta phase, flexible sensors, wearable electronics, all-organic composite, crystallinity, pressure sensing, ferroelectric polymer, fatigue durability

The molecule at the heart of the study is 5-hydroxymethylfurfural, commonly abbreviated as HMF. HMF is a platform chemical derived from lignocellulosic biomass, the woody, fibrous material that plants are largely made of and that is often treated as agricultural waste. When one of HMF’s alcohol groups is selectively oxidized into an aldehyde, the result is 2,5-diformylfuran, or DFF, a compound prized for making polymers, pharmaceuticals, furan-based resins, and a range of fine chemicals. Conventional routes to DFF typically rely on stoichiometric oxidants or energy-intensive thermal processes. Photocatalysis offers an alternative: harvest sunlight, generate energetic charge carriers inside a semiconductor, and use those carriers to drive the oxidation under mild conditions with oxygen as the ultimate oxidant.

The catalyst chosen for this task was cadmium indium sulfide, CdIn2S4, a ternary metal sulfide with a well-earned reputation in the photocatalysis community. Its band gap sits squarely in the visible region of the solar spectrum, meaning it can absorb the abundant visible photons that make up the bulk of sunlight rather than only the small ultraviolet fraction. That property makes it attractive for solar-driven chemistry. But CdIn2S4 has an Achilles heel. When synthesized by conventional routes, it tends to form with poor crystallinity, and the disordered, defect-riddled lattice acts like a trap for the very charge carriers the material is supposed to deliver. Photogenerated electrons and holes recombine rapidly, releasing their energy as heat or light before they can reach the surface and do useful chemistry. The result is a catalyst that absorbs light beautifully but converts little of it into product.

The team’s solution was elegantly simple: crystallinity engineering. Using a hydrothermal synthesis method, in which the material crystallizes from a hot aqueous solution inside a sealed vessel, the researchers tuned the reaction conditions to produce highly crystalline CdIn2S4 with a striking octahedral morphology, which they designated CISH. As a control, they also prepared a low-crystallinity counterpart, CISL, using conditions that yielded the same chemical compound but with a more disordered lattice. Because both materials share the same composition, the comparison isolates crystallinity as the single variable, allowing the researchers to attribute any difference in performance directly to the quality of the crystal lattice rather than to changes in chemistry, composition, or light absorption.

The performance gap was dramatic. Under visible-light irradiation, the highly crystalline octahedral catalyst produced DFF at a rate of 2.56 millimoles per gram of catalyst per hour, approximately 2.3 times the rate achieved by the low-crystallinity material. Equally important, both catalysts maintained selectivity for DFF above 90 percent. Selectivity is the quiet hero of selective oxidation chemistry: HMF contains multiple oxidizable functional groups, and an unselective catalyst will chew through the molecule to produce a mixture of byproducts, including over-oxidized species that destroy the value of the feedstock. Holding selectivity above 90 percent while simultaneously boosting the conversion rate means the improved catalyst is not just faster but genuinely better at the specific transformation the chemists wanted.

To understand why the better crystal wins, the team turned to a battery of photoelectrochemical measurements. Electrochemical impedance spectroscopy revealed that the highly crystalline material has significantly reduced charge-transfer impedance, meaning electrons can move through it and across its surface with less resistance. Linear sweep voltammetry and transient photocurrent measurements showed stronger and more durable photocurrents, consistent with more charge carriers surviving long enough to be collected. Together, the data painted a coherent physical picture: a well-ordered lattice contains fewer defects to act as recombination centers, so photogenerated electrons and holes separate more efficiently, migrate to the surface more quickly, and live longer before they are lost. In photocatalysis, longer-lived carriers mean a greater chance that an electron will reduce an oxygen molecule or that a hole will oxidize an alcohol group before the pair annihilates each other.

Identifying which of those carriers actually does the chemical work was the next question. The researchers performed radical trapping experiments, adding selective scavengers that quench specific reactive species and observing how the reaction responds. When superoxide radicals were scavenged, the reaction slowed sharply; when holes were captured, the same happened. Electron paramagnetic resonance spectroscopy, using a spin-trapping agent, provided direct spectroscopic confirmation that superoxide radical anions are generated on the illuminated catalyst surface. The combined evidence pointed to a two-pronged mechanism in which superoxide radicals, formed when photogenerated electrons reduce dissolved oxygen, and photogenerated holes, left behind in the valence band, act together as the primary reactive species driving the oxidation.

The mechanistic study went a step further and traced the pathway by which HMF becomes DFF. The evidence supports a carbon-centered radical intermediate route: a photogenerated hole abstracts an electron from the alcohol group of HMF, generating a carbon-centered radical on the substrate, which then undergoes further oxidation and deprotonation steps to yield the aldehyde. This level of mechanistic detail matters because it tells future catalyst designers exactly which elementary steps need to be accelerated and which reactive species must be stabilized. A catalyst that excels at producing long-lived holes and efficient oxygen reduction, the study suggests, is precisely the kind of catalyst that will excel at this class of alcohol-to-aldehyde transformations.

Beyond the specific numbers, the study carries a broader design lesson for the field of solar fuels and biomass valorization. Much of the recent effort in photocatalysis has focused on constructing heterojunctions, decorating catalysts with cocatalysts, or introducing vacancies and dopants to tune electronic structure. Those strategies remain powerful, but this work makes the case that crystallinity deserves equal attention as an independent design variable, particularly for ternary metal sulfides, whose synthesis often leaves them defect-rich. The comparison between CISH and CISL shows that two chemically identical materials can differ by more than a factor of two in productivity purely because of how well their atoms are ordered. For a field racing to make solar-driven chemistry competitive with fossil-derived processes, that is a reminder that sometimes the most impactful engineering happens at the level of the crystal itself.

The implications extend to the industrial vision of a biorefinery in which plant waste flows in and high-value chemicals flow out, powered by sunlight. DFF is a gateway to polymers and pharmaceutical intermediates that today are made largely from petrochemical feedstocks, and HMF is available in principle from abundant cellulose and hemicellulose. A photocatalytic route that runs at ambient conditions, uses oxygen as the oxidant, and achieves high rates with high selectivity could dramatically shrink the energy and waste footprint of that chemistry. Challenges remain before such catalysts see the inside of a commercial reactor, including long-term stability, catalyst cost, and scaling hydrothermal synthesis, but the study provides a clear and quantified target: better crystals, longer-lived charges, faster chemistry. In the quiet ordering of atoms within an octahedral particle, the researchers have found a surprisingly potent recipe for making sunlight do useful work on plant-derived molecules.

Subject of Research: Crystallinity engineering of CdIn2S4 octahedral photocatalysts for visible-light selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

Article Title: Enhancing Visible-Light Photocatalytic Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran via Crystallinity Engineering of CdIn2S4 Octahedra

Article References: Ju, Y., Wang, F., Chen, T., Ge, C., Wang, Y., & Tayyab, M. (2026). Enhancing Visible-Light Photocatalytic Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran via Crystallinity Engineering of CdIn2S4 Octahedra. Catalysis Letters, 156(11), Article 304. https://doi.org/10.1007/s10562-026-05546-7

Image Credits: AI Generated

DOI: 10.1007/s10562-026-05546-7

Keywords: photocatalysis, CdIn2S4, crystallinity, 5-hydroxymethylfurfural, 2,5-diformylfuran, biomass valorization, selective oxidation, charge separation, superoxide radicals, visible light, ternary metal sulfides, hydrothermal synthesis

The research team, led by Gen Ma and Dabing Xiang of Chengdu University, set out to compare four fermentation strategies within a single Tartary buckwheat-wheat noodle system. Hollow noodles are big business in China, with the market reaching roughly 12.5 billion yuan in 2023, and most commercial products remain based on refined wheat flour rich in rapidly digestible starch. Fermentation itself, the researchers note, tends to make things worse, increasing the proportion of starch that breaks down quickly in the gut. Long-term consumption of high glycemic index diets is a recognized risk factor for obesity and type 2 diabetes, which makes the search for low-glycemic versions of beloved staples increasingly urgent.

Tartary buckwheat, a pseudocereal packed with dietary fiber, resistant starch, minerals, and bioactive flavonoids, seemed like an obvious candidate to fix the problem. It has documented antioxidant, anti-inflammatory, anti-obesity, and anti-diabetic properties. But there is a catch: buckwheat contains no gluten, the elastic protein network that gives wheat dough its strength. When Tartary buckwheat flour exceeds roughly 30 percent of a noodle formulation, cooking losses climb and quality deteriorates, a limitation that has long constrained its industrial use. The team used a composite flour of 82 percent wheat and 18 percent Tartary buckwheat, supplemented with vital wheat gluten, and then asked a deceptively simple question: does it matter how you ferment it?

The four approaches tested were direct dough fermentation, in which cut noodles or whole dough sheets are fermented after mixing; sourdough fermentation, in which part of the dough is fermented beforehand and then combined with fresh ingredients; liquid pre-fermentation, a so-called reverse fermentation in which a yogurt-like batter made from a portion of the flour, yeast, salt, gluten, and water is fermented for six hours before being blended into the remaining dough; and a combination of liquid pre-fermentation and sourdough methods. An unfermented dough served as the control. Each batch was then subjected to an exhaustive battery of physical and chemical tests, from infrared spectroscopy and X-ray diffraction to rheology, microscopy, texture analysis, cooking trials, and simulated digestion.

The results revealed that fermentation method leaves a distinct fingerprint on starch structure at every scale. All fermented noodles showed increased amylose content, the linear starch molecule that drives gel firmness, with liquid pre-fermentation and sourdough noodles reaching about 26.9 and 26.1 percent respectively, compared with lower values in the unfermented control. Infrared spectroscopy, which tracks the ratio of ordered double-helical starch to amorphous material, showed that every fermentation treatment increased short-range molecular order, with liquid pre-fermentation again leading the field. X-ray diffraction confirmed that the native A-type crystal pattern of the starch was preserved, but the relative crystallinity rose significantly, from 8.46 percent in the unfermented noodles to 13.82 percent in the liquid pre-fermented ones. In other words, fermentation did not create new chemistry; it rearranged existing molecules into a more disciplined architecture.

The mechanism, the authors argue, is a two-part process. Organic acids and microbial enzymes produced during fermentation selectively hydrolyze the amorphous regions of starch granules, stripping away loosely packed material and raising the crystalline share. At the same time, partial debranching of amylopectin side chains releases linear fragments that reassociate through hydrogen bonding into ordered double helices. Scanning electron microscopy provided visual confirmation: fermented noodles showed starch granules coated in amorphous material and embedded in a denser, more continuous network than the loose, discontinuous structure of the unfermented control. Notably, more fermentation was not always better. The sourdough and combined treatments, despite longer total fermentation times, showed lower crystallinity, possibly because excessive acid and enzyme activity hydrolyzed newly formed crystals or cut starch chains too short for efficient stacking.

Those structural differences translated directly into how the noodles behaved, first in the pot and then in the mouth. Fermented noodles cooked faster than the unfermented control, whose optimal cooking time was 172 seconds; sourdough and liquid pre-fermented noodles needed only 102 and 105 seconds respectively, thanks to micropores created by yeast carbon dioxide that speed water penetration and heat transfer. Cooking losses, a measure of how much starch and protein leach into the water, dropped significantly in all fermented groups, with liquid pre-fermented noodles showing the largest reduction at 3.66 percentage points. Texture analysis showed that liquid pre-fermented noodles were significantly harder, chewier, and more resilient than the control, while all fermented groups were less sticky, a combination that aligns closely with consumer preferences. In blind sensory testing by twenty trained panelists, the liquid pre-fermented noodles tied the commercial Tartary buckwheat hollow noodle product for the highest overall score.

The most striking results, however, concerned digestion. Using a standardized in vitro protocol with pepsin, trypsin, alpha-amylase, and amyloglucosidase, the team measured how quickly starch from cooked noodles broke down into glucose. Every fermentation method slowed hydrolysis, but liquid pre-fermentation was the clear winner. Resistant starch, the fraction that escapes digestion in the small intestine, jumped from 32.0 percent in the unfermented noodles to 45.0 percent in the liquid pre-fermented version. The estimated glycemic index fell from 77.61, firmly in the high range, to 66.10, crossing below the threshold of 70 that separates high from medium glycemic foods. The sourdough and combined treatments also achieved medium-glycemic status, while direct dough fermentation fell just short at 71.71.

The researchers attribute the improved digestibility to the same structural reorganization that strengthened the noodles. Ordered crystalline domains and enhanced inter-chain interactions limit excessive starch swelling and make the granule interior less accessible to digestive enzymes, while the protein coating observed on starch granule surfaces appears to impede amylase diffusion. Interestingly, direct dough fermentation achieved a higher resistant starch content than sourdough yet still digested faster overall, suggesting that not all resistant structures are equally stable; its double-helical hydrogen bonds may be weaker and its amorphous regions more labile, allowing enzymes to catch up during the later stages of digestion. This distinction between the amount of resistant starch and its kinetic robustness is one of the study’s more subtle contributions.

The authors are careful to note the limits of their work. The mechanistic analysis focused primarily on starch, and they call for future studies of protein structure and starch-protein interactions to complete the picture. Still, the practical implications are immediate. Liquid pre-fermentation, a technique compatible with modern machine-made noodle production, offers a single process change that simultaneously boosts structural order, improves texture and cooking quality, and shifts a staple food from the high to the medium glycemic category. For a crop like Tartary buckwheat, whose gluten-free nature has long kept it on the margins of industrial food production, the study suggests that the path to high-value functional foods may run not through new ingredients but through a smarter sequence of old ones: ferment the batter first, then build the dough.

Subject of Research: Effects of fermentation methods on starch structure, quality, and digestibility of Tartary buckwheat hollow noodles

Article Title: Liquid pre-fermentation induced starch structural reorganization improves quality and reduces starch digestibility in Tartary buckwheat hollow noodles

Article References: Ma, G., Wang, L., Xu, X., Chen, J., Wang, J., Mei, L., Lu, Y., Wang, L., Li, H., Wan, Y., Zhao, J., Jiang, L., & Xiang, D. (2026). Liquid pre-fermentation induced starch structural reorganization improves quality and reduces starch digestibility in Tartary buckwheat hollow noodles. Food Chemistry: X, Article 104566. https://doi.org/10.1016/j.fochx.2026.104566

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104566

Keywords: Tartary buckwheat, hollow noodles, liquid pre-fermentation, starch digestibility, resistant starch, glycemic index, amylose, crystallinity, food fermentation, noodle quality, X-ray diffraction, functional foods

Starch makes up roughly 60 to 70 percent of the wheat endosperm’s dry weight and is the single most important carbohydrate reserve in the grain. Its functionality is governed by a hierarchy of structural features: the ratio of the two polymers amylose and amylopectin, the molecular weight of those polymers, the branching pattern of the glucose chains, the way amylopectin double helices assemble into crystalline lamellae, and the overall morphology of the granules. Each of these levels influences gelatinization, hydration, retrogradation and other properties that determine whether a flour makes an airy loaf or a dense, gummy one. Because nitrogen controls how carbon is allocated during grain filling, researchers led by Md Najmol Hoque, Clair Keene and Shahidul Islam hypothesized that when nitrogen arrives relative to flowering could produce distinct, measurable changes across this entire structural hierarchy.

To test the idea, the team ran field trials during the 2022 and 2023 growing seasons at four locations in North Dakota and Minnesota — Carrington, Casselton, Prosper and Crookston — using a randomized complete block design with three commercially important hard red spring wheat cultivars: Faller, Frohberg and Glenn. Four nitrogen treatments were compared: an unfertilized control, 56 and 112 kilograms of nitrogen per hectare applied before planting, and a 168-kilogram-per-hectare split treatment that combined pre-plant and starter nitrogen with a post-anthesis top-dress of 33.6 kilograms per hectare during early grain filling. Grain was harvested at physiological maturity, milled in the laboratory, and the resulting flour subjected to an unusually comprehensive battery of analytical techniques spanning scanning electron microscopy, size-exclusion chromatography with multi-angle light scattering, X-ray diffraction, Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, differential scanning calorimetry and solvent retention assays.

The electron microscopy images told the first part of the story. Regardless of nitrogen treatment, the wheat endosperm displayed its characteristic bimodal starch granule population — large lenticular A-type granules and small spherical B-type granules — and nitrogen did not alter the intrinsic shape of individual granules. What changed was their surroundings. Under zero nitrogen, granules sat loosely packed and clearly separated with minimal matrix coverage, but as nitrogen supply increased, packing became progressively more compact and granules became increasingly embedded in a continuous protein matrix. The effect was most pronounced under the split treatment that included post-anthesis nitrogen, consistent with enhanced deposition of storage proteins around the granules during grain filling and a denser, more integrated endosperm microstructure.

The compositional data reinforced this picture. Total starch content declined steadily with increasing nitrogen, from 64.53 percent in the unfertilized control to 62.45 percent under the highest split treatment, presumably because greater nitrogen availability during grain filling favors protein deposition over carbon stored as starch. Yet starch damage during milling actually fell, from 5.08 percent to 4.62 percent, indicating that the denser endosperm matrix physically protected granules from fracture. Flour color shifted in parallel, becoming slightly darker and yellower as protein accumulation altered light scattering within the flour. These coordinated changes show that nitrogen reshapes not only how much starch the grain contains but also how mechanically robust that starch is when the grain meets the mill.

The most striking results concerned the starch polymers themselves. Amylose content followed a biphasic trajectory: it dropped from 26.33 percent in the control to 22.68 percent under the pre-plant 112-kilogram treatment, then partially recovered to 24.49 percent when post-anthesis nitrogen was added. Amylopectin moved in the mirror image, peaking at 77.32 percent under pre-plant nitrogen before easing back. Meanwhile, amylopectin molecular weight rose from 5.76 million daltons in the control to about 8.1 million daltons under nitrogen, while amylose molecular weight fell from 2.05 million to roughly 1.6 million daltons. In other words, pre-anthesis nitrogen pushed the starch toward an amylopectin-rich, high-molecular-weight architecture, whereas late-season nitrogen partially rebalanced the amylose-amylopectin ratio without dismantling the polymer architecture already established.

Structural analyses at the crystalline and molecular scales confirmed that these compositional shifts had real physical consequences. X-ray diffraction showed that all samples retained the characteristic A-type pattern of cereal starch, but relative crystallinity climbed from around 26 percent in unfertilized grain to as high as 33 percent under nitrogen, reflecting more ordered crystalline domains stabilized by the amylopectin-rich composition. Infrared spectroscopy tracked short-range molecular order in the granule’s outer regions and showed the same trend: the ratio associated with ordered structures rose while the amorphous indicator fell. Notably, the degree of branching, measured by nuclear magnetic resonance as the proportion of alpha-1,6 glycosidic linkages, continued to increase even after post-anthesis nitrogen — rising from roughly 2.4 to 2.8 percent in the control to 3.5 to 3.6 percent under the split treatment — whereas crystallinity and molecular order had already plateaued. Branching, it seems, remained responsive to nitrogen availability late into grain filling even after the major structural reorganization was complete.

Those structural differences translated directly into function. Differential scanning calorimetry revealed that gelatinization onset, peak and conclusion temperatures all rose with nitrogen, peaking under the pre-plant 112-kilogram treatment — peak gelatinization temperatures climbed from the low 60s Celsius in unfertilized grain to as high as 71.7 degrees — before easing back under the split treatment. Gelatinization enthalpy followed the same pattern, rising from about 10.5 to 12.3 joules per gram in the control to nearly 17 to 18 joules per gram under pre-plant nitrogen, meaning more energy was needed to disrupt the more highly ordered double-helical and crystalline domains. Hydration behaved differently: swelling power and solubility increased progressively with every increment of nitrogen and kept rising under post-anthesis application, with swelling jumping from 13.15 percent to 19.92 percent and solubility from 16.60 percent to 26.59 percent. Water solvent retention capacity of the flour rose while sodium bicarbonate retention fell, the latter consistent with the reduced starch damage. Late nitrogen, in short, primarily made starch more water-accessible rather than more thermally resistant.

Multivariate statistics tied the whole system together. Principal component analysis of the twelve cultivar-by-treatment combinations showed that the first two components captured 76.9 percent of the total variation, with the dominant axis describing a transition from less ordered to more ordered starch — crystallinity, molecular order, thermal stability and hydration traits all loading together on one side, and total starch, damaged starch and amylose molecular weight on the other. Correlation analysis confirmed that relative crystallinity and infrared-derived order tracked gelatinization temperatures and enthalpy, while swelling and solubility correlated with amylopectin content and structural order. Cultivar mattered too: Frohberg showed the highest gelatinization temperatures and hydration traits, Glenn maintained the highest crystallinity across treatments, and Faller exhibited the greatest branching response, with genotype-by-environment interactions significant for composition and hydration but not for polymer molecular weight, which proved more stable across environments.

The practical implications are considerable. Because pre-anthesis nitrogen chiefly governs composition, crystallinity and thermal behavior, while post-anthesis nitrogen preferentially enhances branching and hydration, fertilizer scheduling could become a tool for tailoring starch functionality to specific end uses — a harder-cooking, more thermally stable starch for one product, a more water-absorbing flour for another — rather than simply maximizing protein content. The authors caution that responses varied in magnitude across site-years that differed in temperature and rainfall, and that future work integrating starch biosynthetic enzyme activity and gene expression will be needed to explain the regulatory mechanisms. But the central message stands: the starch in a wheat kernel is not a fixed commodity. It is a dynamic structure that farmers can, in effect, redesign from the field — one carefully timed application of nitrogen at a time.

Subject of Research: Effects of pre- and post-anthesis nitrogen fertilization on starch structure and functionality in hard red spring wheat

Article Title: Differential regulation of starch structure-function relationships by pre- and post-anthesis nitrogen in hard red spring wheat

Article References: Hoque, M. N., Keene, C., & Islam, S. (2026). Differential regulation of starch structure-function relationships by pre- and post-anthesis nitrogen in hard red spring wheat. Food Chemistry: X, 39, Article 104525. https://doi.org/10.1016/j.fochx.2026.104525

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104525

Keywords: wheat, starch, nitrogen fertilization, post-anthesis nitrogen, amylose, amylopectin, crystallinity, gelatinization, hard red spring wheat, grain filling, food chemistry, flour quality

Researchers led by Siti Nor Hafiza Mohd Yusoff of Universiti Teknologi MARA in Malaysia systematically examined what actually happens when rutile titanium dioxide nanoparticles, with a nominal size below 100 nanometers, are dispersed into PEO and into PEO loaded with lithium perchlorate, one of the classic polymer-salt electrolyte systems. Their findings, published in Discover Industrial Chemistry and Materials, are striking in their consistency: across every composition tested, the nanofiller behaved as an essentially inert passenger. It did not change the glass transition temperature, the heat capacity step, the crystallinity, the melting behavior, the spherulitic morphology, or the ionic conductivity of the host matrix. The particles simply sat there, largely untouched by and un-touching of the polymer around them.

The team prepared free-standing films by solution casting, dissolving PEO, lithium perchlorate, and titanium dioxide in acetonitrile, stirring for 24 hours at 50 degrees Celsius, and then homogenizing the mixture with an Ultra-Turrax at 5000 rpm to minimize agglomeration. The salt concentration was deliberately fixed at a mass fraction of 0.107, a composition thoroughly characterized in the group’s earlier work, so that any observed changes could be attributed cleanly to the nanofiller rather than to shifting polymer-salt interactions. Filler mass fractions ranged from zero up to 0.043 in the ternary system, and every film was carefully dried and thermally annealed to erase any history from the preparation process.

Differential scanning calorimetry provided the first line of evidence. The glass transition temperature of the PEO-lithium perchlorate system dropped from 243 K to roughly 235 K upon the very first addition of titanium dioxide, a shift the authors attribute to a slight weakening of ion-dipole interactions between the polymer and the salt. But beyond that initial step, further increases in filler content produced no significant change whatsoever in the glass transition, the change in heat capacity at the transition, the apparent melting temperature, or the degree of crystallinity, which was calculated against the reference enthalpy of 188.3 joules per gram for perfectly crystalline PEO. In a genuinely miscible system, adding a second component should depress the melting point and reshape the thermal signature of the host. Here, nothing of the sort occurred, a hallmark of phase separation and weak molecular interaction.

The heat capacity data carried particular weight. Because the glass transition reflects the configurational entropy and segmental freedom of amorphous polymer chains, a filler that actively modified the matrix would alter both the transition temperature and the magnitude of the heat capacity step. The researchers normalized their measured values to account for the amorphous fraction of PEO, subtracting the crystalline phase from the total polymer mass, and found the normalized values essentially flat across all filler loadings, with experimental errors below three percent. The mobile amorphous fraction of the polymer, in other words, was preserved intact. The titanium dioxide neither restricted chain motion nor unlocked additional mobility, suggesting it never meaningfully penetrated or perturbed the amorphous regions where ion transport takes place.

Polarized optical microscopy told the same story visually. At room temperature, well below the melting point of PEO at about 65 degrees Celsius, the films displayed the familiar bright spherulitic crystals embedded in dark amorphous regions. Adding even a small amount of filler, at a mass fraction near 0.0089, coarsened the spherulites and increased the apparent nucleation sites, yet the fibrillose architecture of the spherulites remained largely undisturbed. At higher loadings, around 0.043, dark agglomerated patches of titanium dioxide appeared in the matrix, but these micro-scale clusters sat within the polymer without disrupting its crystalline superstructure. The morphology confirmed what the calorimetry implied: an immiscible, phase-separated composite in which the filler and the polymer coexist without meaningful dialogue.

Electrochemical impedance spectroscopy, measured at 25 degrees Celsius from 50 hertz to 1 megahertz with stainless steel blocking electrodes, completed the picture. The Nyquist plots showed the characteristic depressed semicircle and low-frequency spike of a polymer electrolyte dominated by electrode polarization, and equivalent circuit fitting extracted bulk resistance, bulk capacitance, double-layer capacitance, and Warburg impedance elements. The bulk resistance shifted only marginally with increasing filler content, producing conductivities in the same order of magnitude, from 10⁻⁶ to 10⁻⁷ S cm⁻¹, as the filler-free PEO-lithium perchlorate baseline. Bode analysis of the characteristic frequencies of minimum and maximum impedance, along with the crossover frequency marking the onset of dipole percolation, revealed relaxation behavior that stayed within experimental error regardless of loading, reinforcing the conclusion that the nanofiller left the ion transport pathways untouched.

The dielectric analysis added mechanistic depth. The real part of the complex permittivity, which reflects energy storage through dipole polarization, rose steeply at low frequencies due to interfacial polarization at the electrodes, but the addition of titanium dioxide did not promote this polarization. At high frequencies near 10⁶ hertz, the dielectric constant settled to values that showed insignificant variation across all filler fractions. The exponent extracted from the power-law decay of dielectric loss, which distinguishes ideal Debye relaxation with a single time constant from the distributed relaxation typical of heterogeneous systems, remained constant within error. The loss tangent peaks diminished slightly in magnitude and shifted marginally to lower frequencies as filler content increased, indicating a modest reduction in the number of relaxing dipoles, but the overall relaxation landscape was essentially unchanged. Charge transport, the authors conclude, is governed by the molecular interactions among the charged entities of the PEO-lithium perchlorate complex itself, not by any polymer-filler interfacial chemistry.

Why does this matter, and why does it contradict so much of the published literature? Many studies have reported conductivity enhancements from titanium dioxide in PEO electrolytes, typically attributed to Lewis acid-base interactions between surface groups on the nanoparticles and the polymer or salt, which reduce crystallinity and promote ion dissociation. But those outcomes depend critically on nanoparticle surface chemistry, loading, salt type and concentration, polymer molecular weight, preparation route, and dispersion quality. In this study, untreated rutile particles with weak interfacial interaction and a tendency to agglomerate offered little effective surface area for such chemistry to occur. The result is a sobering reference point: nanofiller addition does not inherently guarantee improved electrolyte performance, and the field’s enthusiasm for ceramic additives must be tempered by a clear-eyed assessment of whether genuine polymer-filler interactions actually form.

The practical message for battery designers is twofold. First, establishing strong, deliberate polymer-nanofiller interactions, through surface functionalization or carefully matched chemistry, is essential if fillers are to do real work in solid polymer electrolytes; simply mixing in nanoparticles is not enough. Second, the combined DSC, microscopy, and impedance methodology demonstrated here offers a rigorous template for verifying whether a given filler is an active modifier or an inert bystander in any candidate electrolyte system. As solid-state batteries edge closer to commercial reality, distinguishing the fillers that genuinely enhance ion transport from those that merely add mass will be crucial for rational materials design. This study, by carefully documenting a case of near-perfect inertness, provides exactly the kind of negative result that helps the field calibrate its expectations and redirect its efforts toward interfaces that truly matter.

Subject of Research: The role of titanium dioxide nanofillers in PEO-lithium perchlorate solid polymer electrolytes

Article Title: Inertness of titanium dioxide nanofillers in polyethylene oxide and lithium perchlorate polymer electrolytes

Article References: Hafiza Mohd Yusoff, S. N., Asyqin Zainal, N. F., Sheikh Abdul Aziz, S. S., & Abdul Halim, S. I. (2026). Inertness of titanium dioxide nanofillers in polyethylene oxide and lithium perchlorate polymer electrolytes. Discover Industrial Chemistry and Materials, 1(1), Article 23. https://doi.org/10.1007/s44508-026-00024-9

Image Credits: AI Generated

DOI: 10.1007/s44508-026-00024-9

Keywords: solid polymer electrolytes, poly(ethylene oxide), titanium dioxide, nanofillers, lithium perchlorate, ionic conductivity, differential scanning calorimetry, electrochemical impedance spectroscopy, dielectric relaxation, glass transition, crystallinity, lithium batteries

The research team, led by Jong-Rok Jeon of Gyeongsang National University and Frank Caruso of the University of Melbourne, focused on tannic acid, or TA, a widely available plant polyphenol rich in catechol groups that grip metal ions with remarkable tenacity. Their central hypothesis was elegant: when stressed plants secrete polyphenols into the rhizosphere, the zone of soil hugging the roots, those molecules should coordinate with metal ions in soil minerals such as calcium phosphate, ferric oxide, and aluminum hydroxide, destabilizing the mineral lattices and dissolving nutrients that would otherwise remain locked away.

To test this, the researchers leached soil collected from Jinju in South Korea with TA solutions and analyzed the leachates by inductively coupled plasma optical emission spectroscopy. The results were striking. Aluminum and manganese, undetectable in leachates from untreated soil, appeared at concentrations of roughly ten parts per million when TA was present. Calcium, iron, and magnesium leached at levels up to fifteen times higher, and phosphorus surged to twenty-two times the control values. Even when the soil was first heated to 600 degrees Celsius to burn off organic matter, TA still boosted leaching, though less dramatically, suggesting the polyphenol acts directly on mineral structures rather than merely on organic complexes.

Fluorescence excitation-emission matrices told a subtler story. Leachates from TA-treated soil showed a distinct redshift in their fluorescence signatures compared with both untreated soil leachates and free TA in water, a hallmark of metal-organic coordination. And when the team precipitated mineral-like particles from the leachates, those particles carried up to six times more phenolic content and four to ten times more phosphorus when TA had been present, direct evidence that dissolved metals, phosphate, and polyphenols reassemble together into new hybrid minerals. The authors caution that the TA concentrations used were deliberately high as a proof of concept, so the magnitude of dissolution should not be extrapolated directly to field conditions, but the mechanism itself is clear.

That mechanism carries a tantalizing implication the researchers call soil memory. Because mineral-associated organic matter is notoriously stable, shielded from microbial enzymes by its inorganic armor, polyphenols locked into newly formed minerals could preserve a chemical record of past plant stress, potentially influencing how the soil treats the next generation of plants. Most rhizosphere research has focused on how secondary metabolites sculpt microbial communities; this work adds a slower, geological dimension in which plant biochemistry literally rewrites the crystal structure of the ground.

The team then turned observation into engineering. Using alkaline wet precipitation, they coprecipitated TA with calcium phosphate and with struvite, a phosphorus- and nitrogen-rich mineral recovered from waste streams and increasingly viewed as a sustainable fertilizer alternative. Thermogravimetric analysis confirmed TA loadings proportional to the amount added, and infrared spectroscopy, X-ray photoelectron spectroscopy, and pyrolysis gas chromatography-mass spectrometry all revealed the catechol-metal coordination bonds holding the hybrid together. The calcium-to-phosphorus ratio shifted as TA disrupted the lattice stoichiometry, and solid-state nuclear magnetic resonance showed that the local phosphate environments had been fundamentally altered.

The most consequential change was structural. X-ray diffraction of pristine calcium phosphate showed the sharp peaks of crystalline monetite; with TA incorporated, those peaks broadened and faded, and quantitative crystallinity fell from 67.2 percent to as low as 36.2 percent. Grazing-incidence wide-angle X-ray scattering and electron diffraction confirmed the amorphization, while electron microscopy captured the particles morphing from globular to sharp, wedge-like shapes. The same pattern held for struvite, where TA coordination with magnesium interfered with crystal ordering at both precipitation pH values tested. Disordered, amorphous minerals dissolve more readily than their crystalline counterparts, and the dissolution experiments bore this out: TA-loaded calcium phosphate released up to 85 percent more phosphorus than untreated particles, and TA-loaded struvite released up to twice as much. Crucially, the effect persisted in acidic conditions mimicking root exudates, in acetate buffer, and in humic-acid-containing water, meaning the fertilizers respond to the chemistry of a real rhizosphere.

The payoff came in the greenhouse. Lettuce grown in soil pots treated with TA-loaded calcium phosphate particles produced nearly double the biomass of lettuce grown with plain calcium phosphate, with 3 percent and 8 percent TA loadings performing equally well. Pak choi and corn, grown in different soil types, showed enhancements of up to 2.5-fold, demonstrating that the strategy is not crop- or soil-specific. Tannic acid alone, applied at equivalent amounts, produced only marginal growth, confirming that the benefit arises from the mineral hybridization rather than the polyphenol as a nutrient. Struvite-TA particles delivered a roughly 30 percent biomass increase over plain struvite, and soil DNA analysis revealed that the treated soils were enriched in beneficial microbes, including Lysobacter, Nitrospira japonica, and Adhaeribacter in the calcium phosphate experiments, and Sphingomonas, Massilia, and Chitinophagaceae with struvite, taxa associated with plant growth promotion, stress tolerance, and pathogen suppression.

The synergy appears to be threefold: faster nutrient release from the disordered lattice, co-delivered TA that may stimulate plant physiology and chelate metals to prevent reprecipitation, and a reshaped microbiome tilted toward plant-beneficial species. Because calcium phosphate and struvite can be synthesized from circular-economy feedstocks such as livestock bones and wastewater sludge, and TA is extracted in bulk from renewable plant material, the approach aligns neatly with sustainable agriculture goals. The authors note that metal-phenolic networks are known to evolve structurally during aging, so the low-crystallinity state may even persist or deepen over time, though long-term storage stability remains to be verified.

Significant hurdles stand between bench and field. The cost and scalable supply of TA, optimization of the coprecipitation process for bulk manufacturing, and the economic feasibility of the whole pipeline all require further study, and the authors have filed a patent application covering the technology. Still, the conceptual leap is hard to overstate: a molecule plants already secrete under stress has been shown to govern the crystallinity of soil minerals, and by mimicking that process, researchers have built fertilizers that dissolve on demand, feed beneficial microbes, and grow substantially bigger crops. It is a vivid demonstration that the boundary between plant biochemistry and soil geology is far blurrier, and far more exploitable, than anyone assumed.

Subject of Research: Metal-phenolic complexation between plant polyphenols and soil minerals and its application in low-crystallinity fertilizers

Article Title: Metal–Phenolic Complexation Governs Soil Mineral Crystallinity to Enhance Crop Growth

Article References: Jeon, J.-R., Mazaheri, O., Wang, T., Zavabeti, A., Yoon, H. Y., Phong, N. T., Joe, E.-N., Lin, Z., Pan, S., Kim, C.-J., & Caruso, F. (2026). Metal–Phenolic Complexation Governs Soil Mineral Crystallinity to Enhance Crop Growth. Advanced Science, Article e77994. https://doi.org/10.1002/advs.77994

Image Credits: AI Generated

DOI: 10.1002/advs.77994

Keywords: tannic acid, soil minerals, crystallinity, calcium phosphate, struvite, fertilizer, rhizosphere, root exudates, polyphenols, phosphorus, soil microbiome, sustainable agriculture

The research, led by Chloé Melin of the École de Technologie Supérieure in Montreal and INSA-Lyon, together with Jean-Fabien Capsal, Ricardo Zednik, Angelo Pommella, Nicole Demarquette, and Jean-Marc Chenal, set out to answer a question that has lingered in the literature for years: does PLA actually help PVDF become a better piezoelectric material, or does it merely look like it does on a spectroscopy plot? The team attacked the problem from two processing directions at once. They melt-blended PVDF with PLA at weight ratios of 95/05 and 60/40 using a twin-screw extruder at 210 degrees Celsius, then compression-molded films and stretched them uniaxially at draw ratio 3 across a range of temperatures. In parallel, they prepared the same blend compositions as electrospun fibrous membranes using a semi-industrial twenty-needle unit, with both polymers dissolved together in a dimethyl sulfoxide and acetone mixture.

The central character in this story is the crystal structure of PVDF. The polymer can solidify into several distinct lattice forms, and they are not equal partners. The alpha phase, which forms readily when PVDF cools from the melt, is non-polar and piezoelectrically useless. The beta phase, in which polymer chains adopt an all-trans conformation, is highly polar and delivers the strongest piezoelectric response when the molecular dipoles are aligned by a high-voltage poling treatment. Converting alpha to beta is therefore the name of the game, and the two classic routes are uniaxial stretching of solid films and electrospinning, in which a jet of polymer solution is whipped by intense electric fields into nanometer- and micrometer-scale fibers, combining extreme elongational deformation with rapid solvent evaporation.

Morphology turned out to be the first fork in the road. In the melt-processed blends, scanning electron microscopy revealed that the 95/05 formulation produced a beaded, droplet-in-matrix structure, with discrete PLA domains dispersed in the PVDF, while the 60/40 blend formed a co-continuous architecture in which both polymers formed interpenetrating networks. Differential scanning calorimetry showed that adding PLA left the overall crystallinity of PVDF essentially unchanged at roughly 42 percent, before and after stretching, a consequence of the micrometric PLA domain size and the fact that PVDF crystallizes at a higher temperature than PLA. But the phase composition told a very different story. In the stretched 95/05 blend, the beta-phase fraction matched that of pure PVDF, whereas in the co-continuous 60/40 blend the beta fraction collapsed to 36 percent from the 86 percent achievable in well-processed samples, leaving the material dominated by the inert alpha phase.

The reason for that collapse is a lesson in mechanics. In a co-continuous blend, the macroscopic deformation applied during stretching is shared between the two continuous polymer networks, so the PVDF phase simply never sees enough local stress to drive the alpha-to-beta conformational transformation. Meanwhile, in the beaded 95/05 blend, the team observed cavitation, tiny voids opening at the PVDF-PLA interfaces during stretching, which relaxed local stresses and prevented the hoped-for enhancement of stress transfer to PVDF crystals. Earlier hypotheses in the literature had suggested that PLA could act as a stress concentrator, boosting beta formation through cavitation and heterogeneous deformation. This study’s data call that idea sharply into question: the beta fraction in the stretched blend was no better than in neat PVDF, and in some conditions worse.

Then came the electrical measurements, and the results were even more striking. After poling at 100 volts per micrometer for one hour in dielectric oil, the stretched 95/05 blend showed a piezoelectric coefficient d33 that was 34 to 45 percent lower than pure PVDF stretched under equivalent conditions, despite having a nearly identical beta-phase fraction. The culprit, the researchers showed, is dielectric mismatch. PVDF has a relative permittivity of about 10.8, while PLA’s is only 2.7. During poling, electric field lines preferentially route through the low-permittivity PLA inclusions and through the air-filled cavities left by stretching-induced voids, starving the surrounding PVDF matrix of the field it needs to rotate its dipoles. Finite element simulations in COMSOL Multiphysics, built on a representative volume element containing a PLA inclusion surrounded by an air ellipse, reproduced exactly this field concentration. When the team measured the piezoelectric response of pure PVDF poled at the reduced effective field of roughly 65 volts per micrometer, they obtained a d33 of about 6 piconewtons per coulomb, in close agreement with the blend’s measured value. The physics, in other words, checks out.

The co-continuous 60/40 blend, being overwhelmingly alpha phase, registered no measurable piezoelectric response at all, a d33 of zero. But the electrospinning results added their own twist. Pure electrospun PVDF membranes outperformed their stretched-film counterparts, delivering a d33 roughly 30 percent higher, thanks to about 29 percent greater overall beta-phase content and the superior chain alignment imparted by the enormous elongational forces inside the spinning jet. Interestingly, electrospinning also introduced a significant gamma-phase fraction, an intermediate polar conformation rarely seen in the stretched films, which the authors attribute to the rapid solvent evaporation and extreme deformation rates preserving the initially beta-nucleated chains only partially, letting them relax toward the gamma conformation rather than all the way to alpha.

Yet even electrospinning could not rescue the blend. The electrospun PVDF/PLA 95/05 membranes, despite achieving an electroactive phase fraction of about 86 percent, essentially identical to neat electrospun PVDF, showed a d33 of exactly zero after poling. The team points to a convergence of factors: the finely dispersed, highly elongated PLA domains formed during fiber formation disrupt the local electric field and hinder chain and lamellar orientation; the vastly increased interfacial area places PLA, which is stiffer than amorphous PVDF at the poling temperature, immediately adjacent to the crystal-amorphous interfaces where dipole switching initiates; and interfacial interactions locally stiffen the material, impeding the conformational kinks that must propagate through PVDF chains during poling. Raising the poling temperature triggered electrical breakdown, and lowering the field produced no effective dipole alignment, leaving the membranes piezoelectrically mute.

The study also challenges another widespread assumption. None of the electrospun membranes in this work showed measurable piezoelectric activity before an external poling step, even though the poling field used was nearly twice that of most previous studies reporting self-poled electrospun PVDF. The through-thickness dipole orientation required for a d33 response, the authors note, evidently does not emerge from the electrospinning process alone under these conditions, contradicting a body of literature that has treated self-poling as an intrinsic benefit of the technique.

The broader takeaway is a warning against a seductive shortcut. In the drive toward sustainable, flexible sensors and energy harvesters, blending PVDF with biobased PLA seems like an obvious win: PLA is renewable, biodegradable, stiff, and easy to process. But this work demonstrates that a high beta-phase fraction alone does not guarantee functional piezoelectricity. Electric field distribution, interfacial cavitation, domain size, chain mobility, and processing route all conspire to determine whether a material that looks piezoelectric under an infrared spectrometer actually produces a measurable voltage under stress. For engineers designing the next generation of self-powered wearables and structural health monitors, the message is clear: composition, morphology, and processing must be engineered together, and the role of PLA in enhancing the beta phase of PVDF, once considered promising, is now very much in doubt.

Subject of Research: Piezoelectric performance of PVDF/PLA polymer blends prepared by melt processing and electrospinning

Article Title: Piezoelectric properties of PVDF/PLA blends prepared by melt processing and electrospinning

Article References: Melin, C., Capsal, J.-F., Zednik, R., Pommella, A., Demarquette, N., & Chenal, J.-M. (2026). Piezoelectric properties of PVDF/PLA blends prepared by melt processing and electrospinning. Journal of Materials Science: Polymers, 1(1), Article 13. https://doi.org/10.1007/s44493-026-00010-9

Image Credits: AI Generated

DOI: 10.1007/s44493-026-00010-9

Keywords: PVDF, PLA, piezoelectricity, polymer blends, electrospinning, melt processing, beta phase, energy harvesting, flexible sensors, poling, crystallinity, dielectric permittivity