The choice of base polymer is deliberate. Polyvinylidene fluoride, or PVDF, is a semi-crystalline fluoropolymer prized for its thermal stability, chemical resistance, mechanical strength, and ease of processing, properties that stem from strong dipole interactions between fluorine and carbon atoms along its backbone. It is also piezoelectric and ferroelectric, which has made it popular in sensors and energy devices as well as membranes. But in water treatment, PVDF carries a stubborn flaw: it is intrinsically hydrophobic. Water molecules do not spread readily across its surface, so permeability suffers, fouling takes hold more easily, and operating costs climb as pumps work harder to push water through reluctant pores.

Forward osmosis offers a way around the energy penalty of pressure-driven desalination. Instead of forcing water through a membrane with hydraulic pressure, as reverse osmosis does, FO exploits the natural tendency of water to diffuse from a solution of low osmotic pressure to one of high osmotic pressure. A concentrated draw solution, in this study a 2 molar sodium chloride brine, pulls water across a semipermeable membrane from the feed side. The process runs under mild conditions, achieves high water recovery, and fouls less than pressure-driven systems, but its efficiency hinges on the membrane itself, and hydrophobic PVDF has long been a limiting factor.

Enter hydroxyapatite, the calcium phosphate mineral that gives bones and teeth their strength. The team synthesized ultralong hydroxyapatite nanowires, abbreviated UHA, using a solvothermal method in which calcium chloride, sodium hydroxide, sodium dihydrogen phosphate, oleic acid, water, and methanol were sealed in a Teflon-lined stainless-steel autoclave and heated at 180 degrees Celsius for 24 hours. Oleic acid plays a key role, guiding the mineral to grow into exceptionally long, high-aspect-ratio wires rather than bulky particles. These nanowires are hydrophilic, chemically stable, and biocompatible, and their hydroxyl and phosphate surface groups form strong hydrogen bonds with water and with the surrounding polymer, making them ideal candidates for membrane modification.

Fabrication followed the workhorse route of membrane science: non-solvent-induced phase inversion. The researchers dispersed UHA nanowires in dimethylformamide by stirring and ultrasonication, dissolved PVDF at about 70 degrees Celsius to form a transparent casting solution, and let it rest overnight to release trapped air. The solution was then cast onto glass with a knife set to 200 micrometers and plunged into a water bath, where phase inversion locked in the membrane’s asymmetric structure. Six compositions were prepared, containing 0, 0.1, 0.3, 0.5, 0.7, and 1.0 weight percent UHA relative to PVDF, allowing the team to trace exactly how filler loading reshaped the material.

Characterization told a consistent story across three techniques. X-ray diffraction showed the characteristic PVDF crystalline peak near 2θ of 20 degrees alongside new hydroxyapatite peaks between 25 and 35 degrees, whose intensity grew steadily with loading while the polymer peaks stayed put, evidence that PVDF and UHA interact physically without forming new chemical phases. Infrared spectroscopy confirmed the same picture: hydroxyl bands between 3,200 and 3,500 wavenumbers strengthened with UHA content, phosphate vibrations appeared in the 875 to 1,030 and 560 to 600 regions, and the polymer’s own carbon-hydrogen and carbon-fluorine signatures remained essentially unchanged. Scanning electron microscopy revealed the morphological payoff, with pristine membranes showing semi-dense, poorly defined surfaces while the composites developed homogeneous, interconnected pores and, at 1.0 percent loading, a tangled, carpet-like fibrous network resembling nacre in cross-section.

Wettability measurements tied the chemistry directly to performance. The mean flow pore size rose from about 0.14 micrometers in the pristine membrane to roughly 0.26 micrometers at moderate filler loading, and the water contact angle fell as nanowires accumulated, confirming that the hydroxyl and phosphate groups raised surface energy and eased the membrane’s embrace of water. More hydrophilic surfaces mean less resistance to water transport and fewer opportunities for contaminants to stick. The improvements were not without cost, however. Tensile testing showed Young’s modulus dropping from about 70 to 25 megapascals and elongation at break falling from 600 to 250 percent as UHA content increased, a shift from ductile toward more brittle behavior caused by rigid particles restricting polymer chain movement and creating stress concentration sites.

In forward osmosis tests with distilled water as feed and 2 molar sodium chloride as draw, run for over three hours with mass logged every minute, the membranes delivered water fluxes between 2.1 and 3.6 LMH and reverse salt fluxes between 13 and 66 grams per square meter per hour. The best water flux came at the highest UHA loading, but the selectivity picture was more nuanced. The membrane containing 0.5 percent nanowires, designated M3, showed a notably lower reverse salt flux than the trend, suggesting an optimal balance where improved structural homogeneity suppresses salt transport while preserving water permeability. At higher loadings, additional interfacial pathways appear to open, letting salt slip back toward the feed and eroding the driving force. The authors note that precise control of the additive ratio is therefore essential to reconcile permeability, selectivity, and long-term stability.

The composite membranes also held their performance over time, with no decline in water flux during extended operation, a sign of improved fouling resistance and reduced salt accumulation on the surface. Compared with previously published PVDF-based forward osmosis membranes tested under similar conditions, the PVDF/UHA results fall squarely within the range reported for thin-film composite and modified PVDF systems, validating the fabrication method while pointing to room for further gains. Beyond desalination, the researchers see applications in wastewater treatment and even in separating and concentrating precious metals and dyes from solution, where hydrophilic, fouling-resistant membranes are equally valuable.

What makes the work compelling is its economy of means. Rather than designing an entirely new polymer or resorting to exotic nanomaterials, the team combined two robust, well-understood substances, a durable fluoropolymer and a bone-like calcium phosphate, and let their complementary properties do the work. The nanowires’ extraordinary length allows them to interpenetrate and reinforce the polymer matrix, building interconnected water channels that blunt internal concentration polarization, the hidden enemy of forward osmosis efficiency. The trade-off in mechanical flexibility is real, and the salt selectivity at high loadings still needs tuning, but the study demonstrates that a 70 percent jump in water flux can be achieved with a straightforward blending step. As freshwater demand rises and desalination plants multiply worldwide, such incremental but meaningful improvements in membrane design may prove to be exactly the kind of practical innovation the water sector needs.

Subject of Research: Mixed-matrix PVDF membranes reinforced with ultralong hydroxyapatite nanowires for enhanced forward osmosis desalination

Article Title: Ultralong hydroxyapatite nanowire-incorporated PVDF mixed-matrix membranes for enhanced forward osmosis performance

Article References: Gomaa, M. G., Abdel-Aal, E.-S. A., Russo, F., Galiano, F., Figoli, A., & Abdel-Ghafar, H. M. (2026). Ultralong hydroxyapatite nanowire-incorporated PVDF mixed-matrix membranes for enhanced forward osmosis performance. Frontiers in Membrane Science and Technology, 5, Article 1894848. https://doi.org/10.3389/frmst.2026.1894848

Image Credits: AI Generated

DOI: 10.3389/frmst.2026.1894848

Keywords: forward osmosis, desalination, PVDF, hydroxyapatite nanowires, mixed-matrix membranes, water flux, membrane fouling, hydrophilicity, water treatment, phase inversion, reverse salt flux, nanocomposites

The core problem is wetting. In membrane distillation, a temperature difference between hot saline feed and cold permeate drives water vapor across a porous, hydrophobic membrane. As long as liquid water cannot penetrate the pores, only vapor passes through and salts stay behind. But fouling, scaling, and wetting progressively degrade performance. As salt concentrations approach saturation, crystals nucleate and grow on the membrane surface, gradually transforming it from water-repelling to water-attracting. Once that happens, pores flood, and salt ions leak into the distilled product. Heat loss by conduction and low permeate flux compound the trouble. An effective membrane for this technology therefore needs high hydrophobicity, high porosity, controlled pore size, and strong resistance to wetting, scaling, and fouling all at once — a demanding combination of properties that conventional flat polymer films rarely deliver.

Researchers at the University of Tehran and their collaborators have now reported a strikingly simple way to build such a membrane in a single fabrication step. Writing in the journal Results in Engineering, Kobra Bagheri, Mojtaba Shariaty-Niassar, Javad Karimi Sabet, Abolfazl Dastbaz, and Mahdi Akbari describe a one-step phase-inversion strategy that engineers both surfaces of a polyvinylidene fluoride membrane simultaneously, using nothing more exotic than a roughened glass casting template and a dash of so-called Janus graphene oxide nanosheets dispersed in the polymer solution. The result is a Janus membrane — one with two chemically and physically distinct faces — that nearly doubles water production flux while shrugging off scale formation and running stably for 100 hours on real Caspian Sea water.

The trick relies on two modifications happening at once during non-solvent-induced phase separation, the standard process in which a polymer casting solution is plunged into a coagulation bath and solidifies as solvent and non-solvent exchange. First, the team sandblasted the glass substrate with silica particles to create random micro-roughness. When the PVDF solution was cast onto this template, the membrane surface in contact with the glass inherited the texture, producing a hierarchically rough feed-side surface with random cavities. Second, the researchers added Janus graphene oxide nanosheets — ultrathin sheets with a hydrophilic face and a hydrophobic face functionalized with dodecylamine — to the casting dope at 1 percent by weight relative to the polymer. Because of their asymmetric surface chemistry, these nanosheets spontaneously migrate toward the substrate-contacting side and orient themselves during phase separation, building asymmetric wettability into the membrane without any post-fabrication chemical treatment.

The evidence for this self-assembly is compelling. Energy-dispersive X-ray spectroscopy revealed a clear through-thickness gradient in nitrogen and oxygen, elements characteristic of the nanosheet functional groups: the air-facing top surface contained 8.42 percent oxygen, while the substrate-facing bottom surface contained 20.23 percent, consistent with preferential nanosheet enrichment near the template. Meanwhile, water contact angle measurements confirmed the Janus character. The top surface of the composite membrane was moderately hydrophobic at 73.9 degrees, whereas the patterned bottom surface reached 135.9 degrees — far more water-repellent than either a flat control membrane at 72.7 degrees or a textured membrane without nanosheets at 122 degrees. Interestingly, the bottom surface is chemically richer in hydrophilic groups yet measurably more water-repellent, an apparent paradox the authors resolve through roughness: secondary nano-scale asperities, generated as the orienting nanosheets perturb the demixing front and induce wrinkling, trap air under the droplet in a Cassie–Baxter-type state that drastically reduces solid–liquid contact.

A clever control experiment isolates the synergy. When the same nanosheets were cast onto smooth glass, the contact angle rose by only 6.6 degrees over the plain polymer. On the textured substrate, the identical nanosheet loading raised it by 13.9 degrees — more than double — and scanning electron microscopy showed that only the combination produced the full hierarchical micro-pattern plus secondary roughness. The rough template also prevented membrane shrinkage during coagulation, keeping the film open and porous: the composite membrane achieved 86 percent porosity with a thickness of just 82 micrometers, compared with a dense 65-micrometer flat film. The nanosheets modulate the demixing kinetics, trimming surface pore size to an intermediate 0.35 micrometers — large enough for vapor, small enough to resist liquid intrusion.

Performance in air-gap membrane distillation told the story dramatically. With a 3.5 percent sodium chloride feed at 60 degrees Celsius, the Janus membrane delivered a permeate flux of 16.25 liters per square meter per hour with salt rejection above 99.9 percent — nearly double the 7.75 achieved by the unmodified flat film. When the researchers flipped the membrane so the more hydrophilic face faced the feed, flux collapsed to roughly one-sixth of its normal value while salt rejection held steady, a direct demonstration that the directional Janus architecture is doing functional work: the rough, superhydrophobic face maximizes evaporation area and repels liquid, while the more hydrophilic upper face helps vapor move toward the condensation side.

Resistance to scaling proved equally impressive. In a punishing 12-hour test with a feed containing 7 percent salt plus 1000 parts per million each of calcium and sulfate ions — a recipe for gypsum scale — the flat control membrane held stable for only about four hours before rejection began to fall as crystals accumulated and wetted the pores. The Janus membrane, by contrast, maintained stable flux and rejection throughout all 12 hours, and post-test electron microscopy and elemental analysis showed almost no mineral deposition. The authors attribute this to a near-suspended wetting state in which trapped air creates a slippery interface, raising the energetic barrier to crystal nucleation and shortening the residence time of supersaturated liquid at the surface. After testing, surface sodium content had dropped from 27.08 to 4.19 percent and chlorine from 33.37 to 0.82 percent, indicating the few salt traces could be easily washed away.

Most strikingly, the membrane endured 100 hours of continuous desalination of real Caspian Sea water — a complex matrix with nearly 16,000 parts per million total dissolved solids plus natural organic matter — collected from the coast of Fereydounkenar in northern Iran. Averaging 22.8 liters per square meter per hour, the membrane sustained salt rejection above 99.9 percent for most of the run, easing only to 98.5 percent by the end. Post-run characterization showed the pore structure essentially unchanged at 0.35 micrometers, the contact angle slipping only slightly from 135.9 to 131.0 degrees, and the liquid entry pressure holding at a robust 2.8 bar, while electron microscopy confirmed the template-induced texture had not flattened or delaminated. Compared with previously reported Janus and superhydrophobic membranes — most of which require multi-step patterning followed by fluorination or polymer grafting — this one-step approach stands out for its simplicity, dual-surface engineering, high porosity, and use of a large 32-square-centimeter membrane area with a real seawater feed.

The implications reach beyond a single laboratory result. Membrane distillation has long promised desalination powered by waste heat and sunlight, but membrane failure under scaling and fouling has kept it niche. A fabrication route that turns ordinary phase inversion into self-assembly of an asymmetric, anti-scaling architecture — with no fluorination chemistry, no plasma treatment, and no extra steps — could make such membranes far easier to scale up. The authors even suggest that the distillate quality might allow blending with municipal supplies in Iran’s Mazandaran Province, though they caution that blending ratios and drinking-water compliance remain to be assessed. If the one-step Janus strategy translates from the lab to production lines, the humble two-faced membrane could become a serious contender in the global race to turn seawater into freshwater.

Subject of Research: One-step fabrication of Janus PVDF membranes with template-induced texturing and Janus nanosheet self-orientation for membrane distillation desalination

Article Title: One-step fabrication of PVDF Janus membranes by template-induced texturing and Janus nanosheet self-orientation for membrane distillation

Article References: Bagheri, K., Shariaty-Niassar, M., Sabet, J. K., Dastbaz, A., & Akbari, M. (2026). One-step fabrication of PVDF Janus membranes by template-induced texturing and Janus nanosheet self-orientation for membrane distillation. Results in Engineering, 32, Article 113543. https://doi.org/10.1016/j.rineng.2026.113543

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113543

Keywords: membrane distillation, desalination, Janus membrane, PVDF, graphene oxide nanosheets, phase inversion, superhydrophobicity, anti-scaling, water purification, Caspian Sea water, surface wettability, porous membranes

The research, known as the VISIBLE study, enrolled 180 adults across tertiary and secondary hospitals of the Spanish National Health Service between July 2016 and June 2022. Every participant carried more than one risk factor for incisional hernia, criteria that included age over sixty years, obesity, diabetes, chronic lung or heart disease, smoking, kidney or liver disease, immunosuppression, active cancer and emergency operations. The mean patient age was 64.6 years and the mean body mass index was 27.4 kilograms per square metre. Nearly three quarters of the procedures were performed for cancer, roughly one third were emergencies, and almost a quarter took place in contaminated or dirty surgical fields, settings in which the use of a prophylactic implant has traditionally been considered controversial.

The technique at the heart of the trial was deliberately simple and reproducible. After closing the linea alba with a running long-term absorbable monofilament suture, the surgical team dissected a pocket in the prefascial plane, detached the umbilical scar from the midline, and laid a sheet of polyvinylidene fluoride, or PVDF, mesh over the repaired fascia with an overlap of at least two centimetres at each end. The mesh was fixed with absorbable stitches, the subcutaneous tissue was anchored to its surface to eliminate dead space, and a suction drain was left in place for three to five days. Because the mesh sits on top of the fascia rather than within the abdominal wall’s deeper muscular planes, the operation adds relatively little time and preserves the retromuscular space, a valuable reserve should a hernia ever need formal reconstruction later in life.

What makes the mesh genuinely novel is its chemistry. The implant, manufactured specifically for the study by FEG Textiltechnik in Aachen, Germany, is composed of 90 percent PVDF with a small fraction of triiron tetraoxide woven into its structure. Iron oxide is paramagnetic, which renders the otherwise hard-to-see implant clearly visible on magnetic resonance imaging. This ‘visible’ mesh allowed the investigators to track the implant’s dimensions, position and integrity directly over time, offering a window on mesh behaviour that physical examination alone cannot provide. Each mesh was 35 centimetres long and 7.5 centimetres wide, with a mean pore size of 2.6 millimetres and a weight of approximately 131 grams per square metre.

The results were striking. After two years of follow-up, which reached 96.1 percent of surviving patients, incisional hernia had developed in 21 patients in the intention-to-treat analysis, an incidence of 11.3 percent. When patients with early postoperative wound dehiscence were excluded in the per-protocol analysis, the figure fell to 8.9 percent. Given the clinical profile of the cohort, elderly oncology patients, emergency operations and contaminated fields included, the investigators consider these rates consistent with the lower end of published outcomes for high-risk laparotomy. Notably, three quarters of all hernias occurred among the first ninety patients recruited, hinting that surgical teams became more adept at selecting and managing patients as the study progressed.

Magnetic resonance imaging provided some of the most technically revealing data. MRI was performed in 78.1 percent of patients at six weeks and 65.1 percent at one year, and one hundred patients underwent imaging at both time points. Comparison of the measurements showed that the mesh neither shrank nor distorted significantly: mean length changed from 20.3 to 19.9 centimetres and mean width from 7.02 to 7.04 centimetres, differences that were not statistically significant. Mesh contraction, a well-recognised phenomenon with some synthetic implants that can expose unfilled gaps to rising intra-abdominal pressure, appears to be absent with this material, an observation the authors describe as an important strength of the MRI-based assessment.

Complications were, on the whole, manageable. Surgical-site infection occurred in 12.8 percent of patients during the index admission and seroma in 9.4 percent, although MRI detection pushed the seroma rate to 20.7 percent at six weeks, most of these fluid collections being asymptomatic and invisible on clinical examination. By three months, only 2.4 percent of patients still had a seroma. Mesh removal was ultimately required in four patients, just 2.2 percent of the cohort. Pain, often cited as a fear with mesh implants, was negligible: mean laparotomy pain on a visual analogue scale was 0.2 at three months, and no patient required long-term analgesia or mesh removal for chronic pain. Crucially, emergency surgery and contaminated fields were not associated with a higher rate of mesh-related complications, countering one of the strongest objections to prophylactic implantation.

The statistical modelling identified two independent predictors of hernia formation. Each additional unit of body mass index raised the odds by 19 percent, while patients who required a stoma faced nearly six-fold higher odds, with cumulative incidence at two years of about 27 percent for those with an ileostomy or colostomy compared with 6.3 percent for patients without one. Surprisingly, longer operative time was associated with slightly lower hernia risk, a counterintuitive finding the authors urge readers to treat cautiously, given the observational design and the possibility of residual confounding. Surgical-site infection showed a trend toward increased hernia risk that did not reach statistical significance, and all deaths in the cohort occurred among cancer patients, none related to the mesh.

The study does carry limitations that its authors acknowledge candidly. There was no randomised control group, one hospital contributed nearly 43 percent of patients and 75 percent of hernia events, the multivariable model was built on a modest number of outcome events, and the trial, partly conducted during the COVID-19 pandemic, lacked a standardised fascial closure protocol and validated patient-reported quality-of-life measures. The investigators used Firth penalised regression and bootstrap internal validation to guard against small-sample bias, but they emphasise that the findings are hypothesis-generating and must be confirmed in controlled comparative studies before prophylactic mesh becomes standard practice.

Yet the gap the study addresses is real and persistent. Surveys suggest that while roughly 85 percent of surgeons recognise the benefit of prophylactic mesh reinforcement, only 3 to 15 percent use it routinely, and up to half of patients express concerns about receiving a mesh without an existing hernia. By demonstrating that a simple onlay technique, applied by general surgeons rather than abdominal wall specialists across hospitals of varying size, can achieve a low hernia rate with acceptable morbidity and no significant mesh contraction on MRI, the VISIBLE study makes a persuasive case that the barrier is cultural as much as technical. If larger controlled trials bear out these results, the routine question at the end of high-risk laparotomy may shift from whether to place a mesh to why any surgeon would leave the healing incision unprotected.

Subject of Research: Prophylactic onlay PVDF mesh reinforcement for prevention of incisional hernia after high-risk midline laparotomy

Article Title: Incisional hernia prevention in high-risk midline laparotomy using onlay PVDF mesh: multicenter prospective observational study

Article References: Rodicio Miravalles, J. L., López Monclús, J., Amoza Pais, S., Moreno Gijón, M., López López, A., Gutiérrez Corral, N., Blázquez Hernando, L. A., Menéndez de Llano Ortega, R., Diez Pérez de las Vacas, M. I., Sanz Álvarez, L., & Garcia-Urena, M. A. (2026). Incisional hernia prevention in high-risk midline laparotomy using onlay PVDF mesh: multicenter prospective observational study. Journal of Abdominal Wall Surgery, 5, Article 17201. https://doi.org/10.3389/jaws.2026.17201

Image Credits: AI Generated

DOI: 10.3389/jaws.2026.17201

Keywords: incisional hernia, midline laparotomy, prophylactic mesh, PVDF, MRI visibility, emergency surgery, contaminated surgical field, abdominal wall closure, stoma, surgical site infection, surgical outcomes, Spain

The researchers, Hadi Rouhi and Steven T. Weinman of the Department of Chemical and Biological Engineering, started with commercial polyvinylidene difluoride, or PVDF, ultrafiltration membranes. PVDF is a favorite in water treatment because it shrugs off oxidants, halogens, and most acids and solvents, but its hydrophobic surface gives it little natural affinity for charged pollutants. The team functionalized the membranes with three diamines: 1,3-propanediamine carrying two primary amines, N-methyl-1,3-propanediamine carrying a primary and a secondary amine, and N,N-dimethyl-1,3-propanediamine carrying a primary and a tertiary amine. A fourth variant was created by quaternizing the tertiary amine with iodomethane, producing a permanently charged quaternary ammonium group. The membranes are labeled P, S, T, and Q according to their amine type.

The chemistry behind the modification is itself interesting. Rather than directly displacing the carbon-fluorine bonds of PVDF, the diamines act as bases that drive dehydrofluorination, stripping hydrogen fluoride from the polymer backbone and creating conjugated polyene segments. The amines then attach to some of these newly formed carbon-carbon double bonds through a Michael addition. The visual evidence is striking: the initially white membranes turn brown, darkening progressively from P to Q as more dehydrofluorination occurs. A control experiment with sodium hydroxide, which produces a similar pH but no amines, confirmed that the polyene segments alone do not capture DBSA; it is the amine functionality that does the work.

Characterization backed this up. Attenuated total reflectance Fourier transform infrared spectroscopy revealed new absorption bands at 1532 and 1630 wavenumbers, assigned to N-H bending and C-N stretching, in every diamine-modified membrane. X-ray photoelectron spectroscopy detected a distinct nitrogen 1s peak at 398 electron volts, and the quaternized membrane showed iodine signatures from the methyl iodide reagent. Scanning electron microscopy showed that surface morphology was essentially unchanged, consistent with a monolayer attachment rather than a bulky multilayer coating. Water contact angles shifted only slightly, from 93.2 degrees for unmodified PVDF to 83.0 degrees for the P membrane, again reflecting the thin functional layer.

Performance testing told the central story. Challenged with a demanding DBSA solution of roughly 600 milligrams per liter, far above the 15 to 400 milligrams per liter range typical of adsorption studies, the P, S, and T membranes removed 93.1, 91.4, and 95.3 percent of the surfactant within three hours. The quaternary Q membrane lagged badly, capturing only 37.3 percent in three hours and needing a full day to reach 72.1 percent. Adsorption capacities climbed from a meager 3.9 milligrams per gram for unmodified PVDF to as much as 22.2 milligrams per gram for the modified membranes. The tertiary amine membrane emerged as the fastest and strongest performer, a result the authors attribute to its higher effective positive charge density and the absence of intramolecular hydrogen bonding that would otherwise tie up active sites.

Kinetic analysis added a subtle twist. The P, S, and Q membranes followed pseudo-second-order kinetics, with coefficients of determination of 0.99, while the T membrane was uniquely described by pseudo-first-order kinetics. The team used the corrected Akaike Information Criterion on nonlinear residuals to make the call statistically, a rigorous touch that guards against artifacts of linearization. They interpret the two-stage adsorption profile of the P and S membranes as rapid electrostatic uptake followed by slower, orientation-dependent hydrogen bonding, whereas the T membrane interacts with DBSA through relatively unhindered ion-pairing. The Q membrane showed a sigmoidal profile, suggesting that its bulky trimethylammonium head group and ordered hydration shell must be partially displaced before effective binding can occur.

Isotherm studies pointed to heterogeneous surface interactions. The Temkin model provided the best fit for the P, S, and T membranes, with the adsorption heat constant sitting near 400 to 500 joules per mole for all variants, a hallmark of physisorption. The Sips model, which blends Langmuir and Freundlich behavior, gave the highest capacity and best fit for the T membrane at 21.3 milligrams per gram. Solution pH mattered enormously: removal efficiencies peaked under acidic conditions, where the amine groups are protonated and electrostatic attraction is strongest, and declined as pH rose toward 11, though appreciable removal persisted even there, hinting at hydrophobic and dipole contributions. Background salts of 200 milligrams per liter of sodium chloride or sodium sulfate trimmed removal by roughly 7 to 15 percent, with the T membrane the most ion-sensitive.

Thermodynamics sealed the mechanistic picture. Adsorption was exothermic on every modified membrane, with enthalpy changes of negative 20.0, negative 16.6, negative 27.5, and negative 2.9 kilojoules per mole for the P, S, T, and Q membranes respectively, and isosteric heats ranging from 2.1 to 25.4 kilojoules per mole. All values fall comfortably below the 40 kilojoules per mole threshold conventionally associated with physisorption, confirming that electrostatic attraction and hydrogen bonding, not chemical bond formation, govern the capture. Adsorption became less favorable at elevated temperatures, and the positive entropy changes reflect the release of structured water molecules from the DBSA sulfonate head group and the charged membrane surface as ion-pairs form.

Regeneration results were promising for real-world use. After five adsorption-desorption cycles, using an n-hexane and 1-nonanol mixture to strip the surfactant from the surface, the P, S, T, and Q membranes retained removal efficiencies of 69.9, 68.6, 70.6, and 72.0 percent respectively, down from first-cycle values of 86.6, 88.8, 87.4, and 72.0 percent. Notably, the Q membrane showed almost no decline across cycles, suggesting that its weaker but more reversible interactions resist site fouling. Dynamic flow testing, however, exposed a practical limitation: under continuous-flow conditions with limited residence time, the monolayer functionalization saturates quickly, and the authors suggest that future work should increase surface amine density, perhaps through a thin polymer interlayer, to bridge the gap between static and dynamic performance.

The broader significance is that amine structure is not a cosmetic detail; it is a design lever. Primary and secondary amines bind strongly but can be harder to regenerate, tertiary amines offer the best balance of speed, capacity, and reversibility, and quaternary ammonium groups trade strength for consistency across pH. As surfactant pollution continues to strain sewer networks and treatment plants worldwide, and as roughly one-third of the global urban population already lacks safe drinking water, membranes that can be tuned at the molecular level to capture specific anionic contaminants represent a genuinely exciting direction. This study provides the systematic evidence base for making that tuning rational rather than trial-and-error.

Subject of Research: Primary, secondary, tertiary, and quaternary Alkyl amine-functionalized PVDF membranes for DBSA removal

Article Title: Primary, secondary, tertiary, and quaternary Alkyl amine-functionalized PVDF membranes for DBSA removal

Article References: Rouhi, H., & Weinman, S. T. (2026). Primary, secondary, tertiary, and quaternary Alkyl amine-functionalized PVDF membranes for DBSA removal. Frontiers in Membrane Science and Technology, 5, Article 1892716. https://doi.org/10.3389/frmst.2026.1892716

Image Credits: AI Generated

DOI: 10.3389/frmst.2026.1892716

Keywords: Primary, secondary, tertiary, quaternary, Alkyl, amine-functionalized, PVDF, membranes, DBSA, removal, scientific research

The team, led by Deebhika Selvaraj and Papanasam Esakki, built their membranes from polyvinylidene fluoride, or PVDF, a fluoropolymer prized in the membrane industry for its chemical resistance, thermal stability, and mechanical toughness. PVDF has long served as a workhorse material for water filtration, but on its own it is essentially inert toward dissolved organic contaminants. To give it chemical muscle, the researchers turned to electrospinning, a fabrication technique in which an electric field draws a polymer solution into fibers hundreds of nanometers across. The resulting nonwoven mats boast enormous surface areas and interconnected pore networks, properties that make them ideal scaffolds for capturing molecules from flowing water.

Into this electrospun scaffold the researchers embedded two functional additives. The first was carbon quantum dots, nanoscale carbon particles a few nanometers in diameter that exhibit strong fluorescence and rich surface chemistry. These dots act as adsorption sites and can participate in photoinduced charge transfer, making them popular building blocks in photocatalytic systems. The second additive was titanium dioxide, the archetypal photocatalyst that, when illuminated with ultraviolet light, generates reactive oxygen species capable of shredding organic molecules into smaller, less harmful fragments. By combining the two within the PVDF matrix, the team created a material designed to do two jobs at once: first grab antibiotic molecules from the water, then destroy them under light.

The researchers prepared six different membranes, varying the amount of titanium dioxide loaded onto the carbon-dot-filled PVDF fibers, and then subjected each to a standardized challenge: water contaminated with ciprofloxacin, a fluoroquinolone antibiotic widely used in human and veterinary medicine and frequently detected in environmental water samples. The standout performer was the membrane containing 0.2 percent by weight of titanium dioxide, designated TSPC-2. Under five hours of irradiation from cost-effective UVA lamps, this membrane removed 74.4 percent of the ciprofloxacin in the test solution. That figure represents the combined effect of adsorption onto the fiber surfaces and photocatalytic degradation at the titanium dioxide sites, a dual mechanism the authors argue is key to the membrane’s performance.

Understanding how the membrane works requires a closer look at the chemistry of light-activated titanium dioxide. When photons with sufficient energy strike the semiconductor, they excite electrons from the valence band into the conduction band, leaving behind positively charged holes. These charge carriers migrate to the particle surface, where they react with water and dissolved oxygen to produce hydroxyl radicals and other reactive oxygen species. Hydroxyl radicals are among the most aggressive oxidants known, capable of attacking the ring structures and functional groups of antibiotic molecules. The new study found that degradation efficiency increased with UV intensity, evidence the authors cite as confirmation that hydroxyl radical production by titanium dioxide is driving the photocatalytic half of the removal process.

The kinetics of the removal process followed a pseudo-second-order model, which suggests that the rate-limiting step involves chemical interactions between the antibiotic molecules and the membrane surface rather than simple diffusion. Equilibrium data fit the Langmuir isotherm, indicating that adsorption proceeds through monolayer coverage on a finite number of uniform sites. Together, these two classical models paint a coherent mechanistic picture: ciprofloxacin molecules first adhere to accessible sites across the electrospun fiber network, and once immobilized in close proximity to titanium dioxide particles, they become efficient targets for radical attack under illumination.

Structural analysis added another layer of insight. Using Fourier transform infrared spectroscopy and X-ray diffraction, the researchers probed the crystalline phases of the PVDF matrix. PVDF can crystallize in several distinct phases, and the electroactive beta phase is generally the most desirable for applications involving adsorption and piezoelectric behavior. The spectroscopic and diffraction data confirmed that the incorporation of carbon quantum dots and titanium dioxide promoted an improved beta-phase transition in the polymer. This phase change, the authors suggest, contributes to the membrane’s suitability for combined adsorption and photodegradation, and it illustrates how nanofillers can do more than simply add surface area; they can actively reorganize the host polymer at the molecular level.

Durability is where many promising photocatalytic materials stumble. Nanoparticle slurries can be difficult to recover from treated water, and catalysts often lose activity after repeated use. The Chennai team addressed this concern directly by testing their best membrane through five consecutive reuse cycles. The membrane retained good removal performance across all five, a result the researchers attribute to its mechanical and thermal stability. Because the titanium dioxide and carbon dots are locked within the electrospun fiber mat rather than dispersed freely in solution, the catalyst stays where it is needed and can be lifted out of the water and reused, avoiding the costly separation steps that plague nanoparticle-based treatment schemes.

The broader significance of the work lies in its pragmatism. The researchers deliberately chose inexpensive UVA lamps rather than specialized high-power UV sources, keeping the energy demands of the process within reach of real-world treatment facilities. Electrospinning is an established industrial process, PVDF is already manufactured at scale for membrane applications, and both carbon quantum dots and titanium dioxide can be produced from relatively abundant precursors. The combination points toward treatment modules in which contaminated water passes through a roll of active membrane while sunlight or low-cost UV lamps drive the degradation chemistry, an architecture compatible with existing filtration infrastructure.

Challenges remain before such membranes reach municipal deployment. The study focused on a single antibiotic, ciprofloxacin, and real wastewater contains a cocktail of pharmaceuticals, dyes, heavy metals, and natural organic matter that can compete for adsorption sites and scavenge radicals. Long-term fouling behavior, the toxicity of degradation byproducts, and performance under variable outdoor lighting conditions will all need scrutiny. Still, the demonstration that a 0.2 percent titanium dioxide loading can push ciprofloxacin removal past 74 percent in five hours, with a membrane that survives five reuse cycles, marks a meaningful step. As antibiotic resistance accelerates into one of the defining public health threats of the century, materials that quietly dismantle pharmaceutical residues in water may prove to be among the most consequential tools in the environmental arsenal.

Subject of Research: Nanocomposite PVDF membranes with carbon quantum dots and titanium dioxide for antibiotic adsorption and photocatalytic degradation in water

Article Title: Electrospun PVDF nanocomposite membranes incorporating carbon quantum dots and TiO2 for antibiotics adsorption and photodegradation

Article References: Selvaraj, D., & Esakki, P. (2026). Electrospun PVDF nanocomposite membranes incorporating carbon quantum dots and TiO2 for antibiotics adsorption and photodegradation. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13923-1

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13923-1

Keywords: electrospinning, PVDF, carbon quantum dots, titanium dioxide, photocatalysis, antibiotics, ciprofloxacin, water treatment, nanocomposite membranes, adsorption, hydroxyl radicals, antibiotic resistance

The new binder is built from remarkably humble ingredients: polyacrylic acid and carboxymethyl cellulose, two inexpensive and widely available polymers, crosslinked by citric acid, a common food-grade molecule. What makes this combination powerful is not any single component but the architecture of the network they form together. When the binder is cured, the citric acid creates covalent crosslinks between the polymer chains, while the abundant carboxyl groups along the polyacrylic acid backbone engage in hydrogen bonding with one another and form ionic interactions with the active electrode particles and the metal current collectors. The result is a three-dimensional network that integrates hydrogen, covalent, and ionic bonding simultaneously, a design that solves a long-standing problem in sustainable electrode engineering.

Previous attempts to replace PVDF have often turned to bio-derived binders that can be processed in water, an attractive proposition because water eliminates the need for toxic solvents and dramatically reduces processing costs. However, these bio-based alternatives typically depend on hydrogen bonding alone to hold electrodes together. Hydrogen bonds are individually weak and can break down under the mechanical stresses of battery operation or the harsh electrochemical conditions inside a cell, particularly at high voltages where oxidative degradation becomes a threat. The new crosslinked network overcomes this limitation by layering multiple bonding modes on top of one another. The covalent crosslinks provide permanent structural integrity, the hydrogen bonds offer energy dissipation and flexibility, and the ionic interactions anchor the binder firmly to both active particles and current collectors, delivering strong adhesion along with good oxidative stability and thermal stability.

To test the concept, the researchers fabricated positive electrodes using lithium iron phosphate, a cathode chemistry prized for its safety and longevity in electric vehicles and stationary storage. Electrodes made with the fluorine-free binder delivered an initial capacity comparable to control electrodes made with conventional PVDF, meaning the new binder sacrifices nothing in terms of how much energy the battery can store on first use. More strikingly, the fluorine-free electrodes exhibited better cycle stability than their PVDF counterparts, retaining their capacity more effectively over repeated charge and discharge cycles. This improvement likely stems from the robust multi-bond network, which better accommodates the volume changes and mechanical fatigue that electrodes experience during cycling, keeping active material particles connected to the conductive pathways that carry electrons in and out.

The versatility of the binder chemistry proved to be another key strength. The researchers showed that the same fluorine-free formulation applies to a wide range of both positive and negative electrode materials, suggesting that it is not a niche solution tailored to a single chemistry but a general-purpose platform that could be adopted across the battery industry. This breadth matters enormously for commercialization, because battery manufacturers produce many different electrode chemistries for different applications, and a binder that only worked for one material would offer limited value. A single binder system that works across the portfolio of lithium-ion technologies could simplify manufacturing lines and accelerate adoption.

Perhaps the most consequential finding of the study concerns what happens at the end of a battery’s life. Direct recycling, in which spent electrode materials are recovered and rejuvenated rather than broken down into their elemental constituents, is widely regarded as the most energy-efficient and environmentally friendly recycling pathway. Yet PVDF has been a persistent obstacle to direct recycling because its fluorinated structure generates harmful fluorinated residues during processing and complicates the separation of active materials from the binder matrix. The new fluorine-free binder dissolves this problem. Because it is water-processable and free of fluorine, the researchers were able to demonstrate full recovery of spent positive and negative electrodes, restoring the recovered materials to the same level of performance as pristine ones without generating any fluorinated waste.

The implications of this full-recovery demonstration extend beyond the laboratory. When the team performed a life-cycle analysis comparing batteries made and recycled with the new binder against those based on PVDF, the fluorine-free system showed significant reductions in both energy cost and emissions. This analysis captures the entire journey of the materials, from initial manufacturing through use and into recycling, and it reveals that the environmental benefits compound at every stage. Manufacturing in water instead of N-methyl-2-pyrrolidone saves energy and eliminates toxic solvent handling. Recycling without fluorinated residues avoids hazardous waste streams. And because the recovered electrode materials perform identically to pristine ones, they can re-enter the production loop indefinitely, closing the circle that conventional battery manufacturing leaves stubbornly open.

The research also benefited from sophisticated analytical capabilities. The team used beamlines at the National Synchrotron Light Source II, a U.S. Department of Energy Office of Science user facility operated by Brookhaven National Laboratory, to probe the structure and behavior of their binder system at the molecular level. Such advanced characterization is essential for understanding exactly how the hydrogen, covalent, and ionic bonds distribute themselves within the electrode and how they respond to the stresses of battery operation, knowledge that guides further optimization of the formulation. The work was supported in part by the ECS Toyota Young Investigator Fellowship, reflecting the strong automotive industry interest in sustainable battery technologies, and the researchers have filed a patent application related to the technology, a signal that they see a viable path toward commercial deployment.

What makes this advance resonate beyond the technical community is the elegant simplicity of the underlying idea. Rather than inventing exotic new materials, the researchers combined three inexpensive, well-understood substances in a way that exploits the full spectrum of intermolecular interactions. Polyacrylic acid and carboxymethyl cellulose are already produced at industrial scale for applications ranging from diapers to food thickeners, and citric acid is one of the most abundant organic acids in the world. This means the supply chains and processing knowledge needed to manufacture the binder at scale largely already exist, removing one of the most common barriers that laboratory discoveries face on the road to real-world impact.

As the world electrifies transportation and grids, the volume of lithium-ion batteries reaching end of life is projected to grow into the millions of tonnes per year, making recycling infrastructure not just an environmental nicety but an economic and strategic necessity. Binders have long been treated as a minor, almost invisible component of battery design, yet this study demonstrates that they sit at the very heart of the sustainability challenge, dictating how electrodes are made, how they perform, and how easily their valuable contents can be reclaimed. By replacing a fluorinated polymer and a toxic solvent with a water-based, fully recoverable alternative that actually improves cycle life, the researchers have shown that circularity and performance need not be trade-offs. If the technology scales as hoped, the batteries of the future may be born in water, live longer, and return intact to the factory floor, again and again.

Subject of Research: Fluorine-free polymer binders for sustainable manufacturing and direct recycling of lithium-ion battery electrodes

Article Title: Fluorine-free polymer binder enables circular manufacturing and recycling of lithium-ion batteries

Article References: Lin, J., Mu, A., Tang, W., Li, F., Zhu, Y., Li, M., Yeerella, R. H., Potts, C., Cai, S., Mu, L., Muldoon, J., & Chen, Z. (2026). Fluorine-free polymer binder enables circular manufacturing and recycling of lithium-ion batteries. Nature Communications. https://doi.org/10.1038/s41467-026-78215-3

Image Credits: AI Generated

DOI: 10.1038/s41467-026-78215-3

Keywords: lithium-ion batteries, polymer binder, PVDF, recycling, circular economy, water processing, polyacrylic acid, carboxymethyl cellulose, citric acid crosslinking, life-cycle analysis, lithium iron phosphate, sustainability

The work, led by Yongli Du, Zhenzhu Cao, and Liying Wang at Inner Mongolia University of Technology, tackles a problem that has haunted composite solid electrolytes since their inception. These materials blend the safety and flexibility of polymer membranes with the high conductivity of ceramic ion conductors, and they are widely regarded as key enablers of next-generation lithium metal batteries, which replace the flammable graphite anode of conventional cells with pure lithium metal. In principle, that substitution can dramatically increase energy density. In practice, composite electrolytes have been held back by two chronic weaknesses: ionic conductivity that falls short of liquid electrolytes, and poor compatibility at the interfaces where the electrolyte meets the electrodes. Both flaws shorten battery life and, in the worst case, invite dangerous failures.

The team’s solution centers on halloysite nanotubes, naturally occurring aluminosilicate minerals with a remarkable structural quirk. Each tube is a hollow cylinder roughly a nanometer scale in diameter, and its two ends carry opposite electrical polarities: the outer surface is negatively charged while the inner lumen is positively charged. That built-in asymmetry, the researchers found, is exactly what a struggling composite electrolyte needs. When the nanotubes are dispersed into a matrix of polyvinylidene fluoride, or PVDF, loaded with lithium bis(trifluoromethanesulfonyl)imide salt and garnet-type ceramic particles of a composition known as LLYZTO, the tubes act as bridges, stitching the ceramic particles together into continuous pathways for lithium ions.

The physics behind this improvement is subtle but elegant. In a conventional polymer electrolyte, lithium ions shuffle sluggishly through segmental motion of the polymer chains, while the bulky TFSI anions drift in the opposite direction, creating concentration gradients that degrade performance over time. The negatively charged outer surfaces of the halloysite nanotubes repel the TFSI anions, effectively delaying their diffusion and forcing the current to be carried overwhelmingly by lithium ions. Meanwhile, the positively charged inner channels and the tube surfaces coordinate with the salt, loosening the grip between lithium ions and their anion partners. The result is a dense, percolating network of fast ion conduction that runs between the ceramic particles rather than relying solely on the slow polymer phase.

The numbers reported for the optimized membrane, designated PLLH-7, are striking. Ionic conductivity reaches 8.52 × 10⁻⁴ siemens per centimeter, a figure that places it firmly in the territory once reserved for liquid electrolytes. The lithium-ion transference number climbs to 0.80, meaning that four out of every five charge carriers in the material are lithium ions rather than counterproductive anions, a ratio far above what typical polymer electrolytes manage. Mechanical strength reaches 12.3 megapascals, stiff enough to physically resist the growth of lithium dendrites, the needle-like metal filaments that can pierce electrolytes, short-circuit cells, and in extreme cases ignite fires. Dendrite suppression is arguably the single most important requirement for any electrolyte hoping to survive contact with lithium metal.

Symmetric lithium cells built with the new electrolyte demonstrated just that resilience, cycling stably for 2,400 hours with effective inhibition of dendrite formation. That kind of endurance in a symmetric configuration, where lithium is plated and stripped repeatedly on both electrodes, is a demanding test that many composite electrolytes fail within a few hundred hours. The team then moved to full cells to see how the material would perform in realistic battery chemistry, and the results held up on both ends of the voltage spectrum.

Paired with a lithium iron phosphate cathode, the material of choice for rugged, long-life batteries, the cell retained a discharge capacity of 131.6 milliampere-hours per gram after 350 cycles at a 0.2C rate, with a Coulombic efficiency of 95.4 percent. More impressively, when the electrolyte was matched with a nickel-rich NCM811 cathode, the high-voltage chemistry favored in electric vehicles for its energy density, the cell maintained 124.1 milliampere-hours per gram after 500 cycles at 1C. Sustaining that capacity at high voltage and high rate suggests the electrolyte resists oxidative degradation at the cathode interface as well as reduction at the anode, a dual tolerance that few polymer-based systems achieve.

What makes the advance particularly compelling is the raw material itself. Halloysite is a naturally abundant clay, chemically similar to kaolin, and it can be mined and processed at a fraction of the cost of engineered nanomaterials such as carbon nanotubes or synthesized ceramic whiskers. Its use here follows a growing body of evidence that one-dimensional fillers outperform spherical nanoparticles in composite electrolytes, because their elongated geometry allows them to form connected networks at much lower loadings. Earlier studies have shown similar benefits with oxide nanowires and beta-alumina nanowires, but halloysite brings the added advantage of its intrinsic dipolar surface chemistry, which the authors exploit to simultaneously accelerate lithium transport and suppress anion motion.

The study also fits into a broader strategy emerging across the solid-state battery field: rather than inventing entirely new chemistries, researchers are learning to orchestrate the interfaces within composite materials so that each component does what it does best. The garnet ceramic particles provide rigid, fast-conducting domains; the PVDF matrix provides flexibility, processability, and thermal stability; the lithium salt supplies mobile ions; and the nanotubes knit the whole assembly into a coherent transport architecture. The authors describe the approach as an effective method for improving the ionic conductivity, mechanical properties, and electrochemical performance of PVDF-based composite electrolytes, and the same design logic could plausibly extend to sodium and other emerging battery chemistries where halloysite has already shown promise.

Challenges remain before clay-toughened electrolytes find their way into commercial cells. Scaling up thin, defect-free membranes to the square meters required for automotive packs is notoriously difficult, and the long-term behavior of polymer-ceramic interfaces under thermal stress and high stack pressure still needs validation. The Coulombic efficiency of 95.4 percent, while respectable, leaves room for improvement compared with the best liquid systems. Nevertheless, the demonstration that a cheap, naturally occurring nanotube can transform the transport properties of a composite electrolyte offers a vivid reminder that in battery science, sometimes the most powerful tools are dug straight out of the ground. If the approach survives scale-up, the humble halloysite tube may earn a place inside the batteries that power the next generation of electric vehicles.

Subject of Research: Halloysite nanotube-reinforced composite solid electrolytes for lithium metal batteries

Article Title: Highly efficient ionic transport networks by one-dimensional HNTs to enhance the performance of composite solid electrolytes for lithium metal batteries

Article References: Du, Y., Cao, Y., Cao, Z., & Wang, L. (2026). Highly efficient ionic transport networks by one-dimensional HNTs to enhance the performance of composite solid electrolytes for lithium metal batteries. Ionics. https://doi.org/10.1007/s11581-026-07481-4

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07481-4

Keywords: solid-state batteries, composite solid electrolytes, halloysite nanotubes, lithium metal batteries, ionic conductivity, PVDF, garnet electrolyte, lithium dendrites, transference number, LLYZTO, energy storage, nanocomposites

The central idea behind the study is division of labor at the nanoscale. Bismuth oxide, in its alpha crystalline phase, is the redox workhorse of the electrode, shuttling charge through fast surface and near-surface reactions that give pseudocapacitors their battery-like storage capacity. Multi-walled carbon nanotubes contribute the opposite virtue: an electrically conductive, graphitic scaffold that lets electrons flow freely through the film, so that no particle of active oxide is ever more than a few nanometers from a current pathway. Precipitated calcium carbonate, a material more often associated with paper fillers and paints than with cutting-edge electrochemistry, plays the role of structural stabilizer, helping to maintain an open, interconnected mesoporous architecture that keeps electrolyte ions moving freely even when the electrode is packed with active material.

Verifying that all three components genuinely coexist, and cooperate, required an extensive characterization campaign. X-ray diffraction confirmed the presence of alpha-phase bismuth oxide, calcite-form calcium carbonate, and graphitic carbon nanotubes within the composite, while Fourier transform infrared spectroscopy added complementary chemical fingerprints of each constituent. Field-emission scanning electron microscopy revealed the morphology of the films, showing an interconnected network in which the different phases are intimately mixed rather than segregated. Brunauer-Emmett-Teller analysis of gas adsorption quantified the textural properties, confirming a mesoporous structure with pores in the size range that allows electrolyte ions to penetrate rapidly and access the interior surfaces of the electrode, a prerequisite for high-rate performance.

The electrochemical results are where the ternary design earns its keep. In cyclic voltammetry and galvanostatic charge-discharge tests, the Bi2O3/PCC/MWCNT composite achieved the highest specific capacitance of all electrodes investigated, reaching 1359.5 farads per gram at 1 ampere per gram. Even when the current density was raised tenfold to 10 amperes per gram, the electrode still delivered 899.6 farads per gram, a rate retention of 66.2 percent. That figure matters because it demonstrates that the composite does not merely store a lot of charge under gentle conditions; it can also release that charge quickly, which is precisely what supercapacitors are asked to do in applications ranging from regenerative braking to grid frequency regulation.

Energy density, the metric that determines how much work a stored charge can actually perform, tells an equally striking story. In a three-electrode half-cell configuration, the composite delivered 196 watt-hours per kilogram at 1 ampere per gram, a value that rivals some lithium-ion battery chemistries and far exceeds the 5 to 10 watt-hours per kilogram typical of commercial carbon-based supercapacitors. Electrochemical impedance spectroscopy helped explain why: the composite exhibited a charge-transfer resistance of just 0.87 ohms, an exceptionally low value indicating that ions and electrons move across the electrode-electrolyte interface with minimal obstruction. The authors attribute this to the cooperative contributions of the redox-active bismuth oxide, the conductive nanotube network, and the structurally stabilizing calcium carbonate phase working in concert.

The fabrication route is as noteworthy as the materials themselves. Rather than casting a conventional slurry onto a metal foil, the team employed an electrospinning-assisted coating approach, drawing the PVDF/DMF solution loaded with the three active components into fine fibers that deposit as a porous, high-surface-area film. Electrospinning has become a favored technique in flexible energy storage because it naturally produces interconnected fibrous networks with tunable porosity, and the group’s earlier work on MXene-PVDF fibers and flower-like MoS2 and MXene electrodes suggested that the method could be adapted to a wider palette of active materials. The present study extends that strategy to a ternary oxide-carbonate-carbon system, demonstrating that the polymer matrix can host chemically dissimilar phases without sacrificing structural integrity.

Long-term durability, however, remains the honest caveat in an otherwise impressive dataset. When the composite was cycled continuously at a demanding 30 amperes per gram for 10,000 cycles, it retained 37 percent of its initial capacitance. That retention exceeded that of the bismuth-oxide-only and nanotube-only electrodes, suggesting that the ternary architecture does buffer some of the degradation mechanisms that plague pure pseudocapacitive materials, such as volume changes during repeated redox reactions. Yet it remained below the retention of the PCC-only electrode, a reminder that high energy density and long cycle life often pull in opposite directions, and that the mechanical and chemical stresses of rapid cycling still take a measurable toll on the composite structure.

The choice of calcium carbonate as the third component is the study’s most unexpected contribution, and arguably its most interesting from a materials-design standpoint. Precipitated calcium carbonate is abundant, inexpensive, and produced at industrial scale, which makes it an attractive structural additive if it can genuinely improve electrode performance. Prior studies have explored carbonate nanoparticles in porous composite electrodes and even built asymmetric supercapacitors around nanostructured calcium carbonate, but incorporating it as a deliberate stabilizing phase within an established bismuth oxide/carbon nanotube system is a new twist. The results suggest that PCC helps preserve the mesoporous network during fabrication and cycling, preventing the collapse or agglomeration that would otherwise choke off ion transport and erode capacitance over time.

Bismuth oxide itself has been enjoying renewed attention in the energy storage community. Compared with heavier investment favorites such as ruthenium oxide or nickel cobaltites, bismuth is relatively inexpensive, environmentally benign, and offers a rich redox chemistry that can be exploited in aqueous electrolytes. Recent years have seen bismuth oxide paired with reduced graphene oxide, hierarchical porous carbon, and polyaniline, each combination attempting to solve the same twin problems of poor intrinsic conductivity and structural degradation. The Turkish team’s contribution to this crowded field is the demonstration that a three-way composite, engineered through electrospinning-assisted coating in a PVDF/DMF matrix, can achieve both high capacitance and favorable rate capability simultaneously, something that binary combinations in the same study could not match.

What comes next is clear from the authors’ own assessment: the ternary architecture provides high specific capacitance and strong rate performance, but further optimization is required to improve long-term cycling durability. Potential strategies, consistent with the broader literature, include refining the ratio of the three components, engineering protective coatings around the bismuth oxide particles, and tuning the electrospinning parameters to produce even more resilient fiber networks. If the durability gap can be closed without sacrificing the remarkable capacitance and low charge-transfer resistance already achieved, the humble trio of bismuth oxide, chalk, and carbon nanotubes could find a genuine place in the next generation of high-power energy storage devices, proving once again that in materials science, the most unglamorous ingredients sometimes deliver the most electrifying results.

Subject of Research: Ternary Bi2O3/PCC/MWCNT composite electrodes in a PVDF/DMF matrix for supercapacitor applications

Article Title: Comparative investigation of the electrochemical performance of Bi₂O₃, PCC, and MWCNT-based composites in a PVDF/DMF matrix for advanced electrode applications

Article References: Unlu, I., Dokan, F. K., Battaloglu, R., & Sahmetlioglu, E. (2026). Comparative investigation of the electrochemical performance of Bi₂O₃, PCC, and MWCNT-based composites in a PVDF/DMF matrix for advanced electrode applications. Ionics. https://doi.org/10.1007/s11581-026-07514-y

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07514-y

Keywords: supercapacitors, bismuth oxide, precipitated calcium carbonate, multi-walled carbon nanotubes, PVDF, electrospinning, ternary composite electrode, specific capacitance, energy density, electrochemical impedance spectroscopy, pseudocapacitance, mesoporous architecture

Base isolation is one of the most successful strategies in modern earthquake engineering. The basic idea is to decouple a structure from the ground beneath it by inserting flexible bearings between the foundation and the superstructure, so that violent ground motions are filtered out before they reach the floors above. Conventional isolation systems, however, are largely passive: once installed, their stiffness and damping properties are fixed, and they cannot adapt to the particular frequency content or intensity of an incoming earthquake. Active and semi-active control systems can adapt, but they typically require external power supplies, which raises a vexing practical question during exactly the events they are designed for, when electrical grids are among the first pieces of infrastructure to fail.

The Turkish team’s hybrid concept addresses that vulnerability by closing the energy loop inside the isolation system itself. PVDF is a flexible piezoelectric polymer that generates an electrical charge when it is mechanically deformed. In the proposed system, PVDF layers are integrated into the base isolation mechanism, where the relative displacements and strains produced during shaking deform the polymer and generate voltage. Numerical modeling carried out in the finite element software ANSYS confirmed that these layers can convert seismic-induced strains into usable electrical energy, which then powers electromagnets to produce control forces that oppose the motion of the structure. In effect, the earthquake charges the system, and the system spends that charge damping the earthquake.

The self-powered character of the design is what makes the results striking. In the experimental campaign, the PVDF layers generated voltage outputs of up to 102 volts, demonstrating the feasibility of operating the electromagnetic control stage without any external power source. The authors are careful to note the caveats: the measured voltage outputs may vary depending on the structural irregularities of the building and on the frequency content of each earthquake, and the repeatability of the results is subject to the experimental and scaling limitations inherent in laboratory testing. Even so, a hundred-volt-class output harvested from a scaled shaking table test represents a meaningful proof of concept for energy-autonomous structural control.

The experimental program was unusually thorough for a study of this kind. The researchers built eight steel frame models at 1/10 scale and tested them on a shaking table under eleven representative earthquake records from Türkiye, a country that sits on some of the most active fault systems in the world and suffered devastating earthquakes in Kahramanmaraş in 2023. Crucially, the eight models were not all identical. The team included both regular configurations and irregular ones, specifically frames with torsional irregularity, soft-story conditions, and vertical discontinuity. These irregularity classes are among the most dangerous features in real buildings, because they concentrate seismic demand in unpredictable locations and have been implicated in many collapse events.

Testing across such a diverse set of structural configurations matters because base isolation does not perform uniformly on all buildings. Irregular structures respond to ground motion in complicated ways: torsionally irregular frames twist as well as translate, soft stories concentrate deformation in a single vulnerable level, and vertical discontinuities create abrupt changes in stiffness and mass that can amplify local response. A control system that works well on a regular, symmetric laboratory model may behave very differently on a real building with a tall open ground floor or a setback upper story. By subjecting all eight configurations to the same battery of eleven ground motions, the study provides a more realistic picture of how the hybrid system performs across the messy variety of the actual building stock.

The underlying physics of the system draws on two well-established research streams that have rarely been merged at the base of a building. Piezoelectric energy harvesting has been explored for decades in contexts ranging from instrumented knee implants to pavement-embedded transducers that generate power from footsteps, and researchers have long recognized that structural vibrations could power wireless sensors and small devices. Electromagnetic damping and electromagnetic isolation, meanwhile, have been studied as means of providing tunable, controllable restoring and dissipative forces without mechanical contact. The innovation in the new work lies in coupling the two: the piezoelectric layer acts as both a sensor of structural strain and a generator of the electricity that the electromagnetic actuator consumes, eliminating the need for a separate power and sensing infrastructure.

The study builds on a doctoral thesis completed at Atatürk University and was supported by the university’s Scientific Research Projects Coordination Unit under project numbers FKP-2023-12377 and FBG-2022-11620. The research sits within a broader international effort, documented in recent review literature, to develop smart and hybrid isolation systems, some of which envision integration with earthquake early warning networks. What distinguishes the PVDF-based approach is its sustainability argument: rather than dissipating seismic energy purely as heat in viscous or frictional elements, the system captures a portion of that energy, converts it to electricity, and redeploys it as active control force, improving structural resilience while providing what the authors describe as sustainable seismic energy dissipation.

The implications for both existing and newly designed buildings could be significant. Retrofitting vulnerable structures is one of the great unsolved challenges of earthquake engineering, particularly in seismically active, economically constrained regions, and any technology that reduces dependence on external power and complex control hardware lowers the barrier to adoption. Because the hybrid system operates at the base of the structure, it could in principle be incorporated into isolation layers added beneath existing buildings or designed into new foundations from the start. The authors report that the overall findings confirm the hybrid system improves structural resilience while offering a promising pathway for both categories of construction.

Considerable engineering work remains before such a system could be specified for a real building. The experiments were conducted on 1/10-scale models, and scaling effects mean that voltage outputs, force magnitudes, and control performance at full scale cannot be read directly from these results. The sensitivity of the harvested voltage to earthquake frequency content means that the system’s self-sufficiency would need to be verified across the full spectrum of possible ground motions, including near-fault pulses with long-period velocity components that pose particular challenges for isolated structures. Power conditioning, energy storage, and the reliability of electromagnetic actuators under sustained seismic loading would all require dedicated development. Yet the core demonstration, that a building’s foundation can harvest the energy of an earthquake and immediately spend it protecting the structure above, stands as a compelling glimpse of where structural control may be heading: toward buildings that do not merely endure earthquakes, but feed on them.

Subject of Research: A PVDF-based hybrid base isolation system that harvests seismic energy to power electromagnetic vibration control

Article Title: Seismic energy dissipation and vibration mitigation through a PVDF-based hybrid base isolation system with electromagnetic control

Article References: Çelebi, O., & Aydın, A. C. (2026). Seismic energy dissipation and vibration mitigation through a PVDF-based hybrid base isolation system with electromagnetic control. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02671-x

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02671-x

Keywords: base isolation, PVDF, piezoelectric energy harvesting, electromagnetic damping, seismic energy dissipation, shaking table tests, structural control, structural irregularities, earthquake engineering, vibration mitigation, self-powered systems, steel frame models

Polyvinylidene difluoride, or PVDF, has long been a favorite of flexible electronics engineers because it combines the mechanical resilience of a plastic with genuine piezoelectric behavior. The catch is that piezoelectricity in PVDF depends entirely on which of its several crystal phases dominates. The nonpolar alpha phase, which forms under ordinary processing conditions, contributes essentially nothing to energy conversion. The polar beta phase, in which the fluorine and hydrogen atoms on the polymer chain are arranged so that each unit cell carries a permanent dipole moment, is the phase that actually generates charge when the material is stretched or compressed. In untreated electrospun PVDF fibers, the beta-phase fraction typically hovers around two-thirds of the crystalline content, leaving considerable room for improvement.

The Pakistani-led team attacked this problem by dispersing BST particles throughout the polymer solution before electrospinning it into fibers. Electrospinning itself already helps: the intense electric field applied as the polymer jet is drawn toward the collector stretches the chains and encourages them to fold into the polar beta configuration. The researchers found that the ceramic particles act as nucleation sites that amplify this effect. Their negatively charged surfaces attract the positively polarized CH2 groups of the PVDF chains, locking the polymer into the all-trans beta conformation as the fiber solidifies. The result, confirmed by both X-ray diffraction and Fourier transform infrared spectroscopy, was an increase in beta-phase content from roughly 65.7 percent in pristine PVDF fibers to about 87.4 percent at the optimal filler loading.

That optimum turned out to be 30 weight percent BST. The team systematically tested loadings of 10, 20, 30, 40, and 50 weight percent, and the structural measurements showed the polar fraction rising steadily up to the 30 percent mark before declining again at higher concentrations. The decline at high loadings is a familiar pattern in composite piezoelectrics: once too much ceramic is packed into the matrix, the particles begin to agglomerate, disrupting the polymer chains instead of aligning them and simultaneously making the fibers stiffer and more brittle. The sweet spot balances nucleation benefits against these aggregation penalties, and the spectroscopic data pinpointed it precisely.

The electrical payoff was substantial. Piezoelectric nanogenerators built from the optimized 30 percent BST/PVDF composite fibers delivered an open-circuit voltage of about 23.3 volts and a short-circuit current density of roughly 0.194 milliamperes per square meter, with a maximum power density of approximately 4.52 milliwatts per square meter measured at a load resistance of 60 megaohms. By comparison, devices made from the pristine PVDF fibers produced an open-circuit voltage of only about 11.8 volts, a current density of about 0.118 milliamperes per square meter, and a peak power density near 1.39 milliwatts per square meter at 50 megaohms. In other words, the ceramic additive roughly doubled the voltage and more than tripled the power output, a leap that stems directly from the higher density of aligned dipoles available to respond to mechanical strain.

The mechanism behind this enhancement involves more than simple nucleation. Barium titanate is itself a classic ferroelectric perovskite, and substituting a small fraction of strontium for barium modifies its lattice in ways that previous studies have linked to improved piezoelectric and dielectric response. When the BST particles are embedded in the polar polymer matrix, local electric fields around the ceramic inclusions interact with the dipoles of the surrounding PVDF chains, and the electrospinning process ensures that both components are oriented along the fiber axis. The composite therefore benefits from the flexibility and processability of the polymer alongside the strong polarization of the ceramic, with the interface between the two phases acting as the critical region where charge transfer and dipole coupling take place.

To demonstrate that the devices could do real work, the researchers connected their nanogenerators to practical loads. The BST/PVDF fiber devices were able to illuminate multiple light-emitting diodes and to power a digital multimeter and a hygrometer, the kind of low-power electronics that define the growing internet of things. This demonstration matters because many piezoelectric energy harvesters reported in the literature produce impressive voltage numbers on an oscilloscope but deliver too little current or power to drive anything tangible. Showing that the composite fibers can sustain multiple LEDs and run measurement instruments places the material firmly in the category of functional, application-ready energy harvesters rather than laboratory curiosities.

The broader context is the surging demand for sustainable power sources in flexible and wearable devices. Sensors for health monitoring, motion tracking, and environmental measurement are proliferating, but batteries impose weight, rigidity, charging requirements, and eventual disposal problems. Piezoelectric nanogenerators offer an alternative: they scavenge energy from the very motions that the devices experience, whether that is a footstep, a heartbeat, a breeze, or the flexing of a fabric. PVDF-based systems are particularly attractive for these roles because they are lead-free, unlike the widely used lead zirconate titanate ceramics, and because electrospinning can produce them as soft fiber mats that integrate naturally into textiles and conformal coatings. The challenge has always been output, and the BST strategy reported here represents a straightforward, scalable route to closing that gap.

The choice of strontium doping level also reflects a deliberate design decision grounded in the ceramics literature. Prior work on Ba1-xSrxTiO3 systems has shown that modest strontium substitution can tune the ferroelectric transition temperature and enhance piezoelectric coefficients in the resulting ceramics, while higher substitution levels shift the material toward different structural regimes. By fixing the composition at Ba0.96Sr0.04TiO3, the team selected a formulation with favorable polarization characteristics and then focused their optimization effort on the parameter that mattered most for the composite: the filler concentration. This two-stage design logic, tuning the ceramic first and the composite second, offers a template that other groups working on related systems, from KNN/PVDF to PZT/PVDF composites, can readily adapt.

Funded in part by the Higher Education Department of Khyber Pakhtunkhwa through its Higher Education Research Endowment Fund, and carried out in the Nano Physics Laboratory at Abdul Wali Khan University Mardan, the study adds to a rapidly expanding body of work on PVDF composite fibers for energy harvesting. The authors suggest that their BST/PVDF composite fibers could serve as high-efficiency piezoelectric materials for sustainable energy sources in flexible electronic devices, and the numbers support that claim. With beta-phase content near 87 percent, voltages above 23 volts, and power densities exceeding 4.5 milliwatts per square meter from a lead-free, textile-compatible platform, the material brings self-powered wearables a practical step closer to reality, and it does so using processing techniques that are already compatible with large-scale fiber manufacturing.

Subject of Research: Strontium-doped barium titanate enhancement of beta-phase PVDF composite fibers for flexible piezoelectric energy harvesting

Article Title: Barium strontium titanate induced β-phase enhancement in electrospun polyvinylidene difluoride composite fibers for high-efficiency flexible piezoelectric nanogenerators

Article References: Khan, S., Din, J. U., Shah, S. K., Ali, N., Saleem, S., Yousaf, J., Rauf, M., & Hayat, K. (2026). Barium strontium titanate induced β-phase enhancement in electrospun polyvinylidene difluoride composite fibers for high-efficiency flexible piezoelectric nanogenerators. Polymer Bulletin, 83(12), Article 655. https://doi.org/10.1007/s00289-026-06719-5

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06719-5

Keywords: PVDF, barium strontium titanate, BST, piezoelectric nanogenerator, electrospinning, beta-phase, energy harvesting, flexible electronics, composite fibers, wearable devices, lead-free piezoelectrics, power density