The material is based on a class of sulfur-containing molecules known as 1,2-dithiolanes. The Surrey team’s study, published in Macromolecules, investigates polymers made from a specially designed lipoic-acid-derived building block, described in the paper as “lipoic acid without the side chain.” In polymer chemistry, small molecular units called monomers are joined through chemical reactions to create long chains. Those chains determine whether a material behaves like a soft film, a rigid solid, a rubber or a liquid. In this case, the monomer’s strained five-membered disulfide ring gives the polymer unusual chemical reversibility, allowing the long chains to break apart and reform under controlled conditions.

Most everyday plastics are valuable precisely because their molecular structures are difficult to disrupt. Polyethylene, used in carrier bags, food packaging and shampoo bottles, consists of stable carbon–carbon backbones that do not readily return to their original building blocks. Mechanical recycling can turn such plastics into lower-quality products, but chemical recycling is more demanding because the polymer must be broken down and the resulting compounds often require purification and further chemical processing. Even many polymers designed for chemical recycling need temperatures of approximately 150 to 200 degrees Celsius before depolymerisation becomes efficient. The Surrey material follows a different path, breaking down at about 90 degrees Celsius and producing a vapour rather than a liquid mixture of recovered monomers.

Depolymerisation is the reverse of polymerisation: instead of joining monomers into long molecular chains, it separates those chains back into their constituent units. When the Surrey polymer is heated, the bonds connecting the repeating 1,2-dithiolane-derived units can undergo a reversible ring-opening and ring-closing process. The polymer therefore loses its large-chain structure and converts into small molecules with sufficient volatility to enter the gas phase. As the vapour cools, the molecules condense and spontaneously polymerise, rebuilding the original material. This behaviour resembles sublimation and deposition more closely than conventional melt processing, because the polymer can move directly between a solid surface and a vapour without first passing through an ordinary liquid state.

That physical transformation could make the material particularly useful as a coating. To demonstrate the concept, the researchers generated a vapour from the polymer and allowed it to condense onto a surface, forming a continuous waterproof layer. Vapour deposition can reach areas that are difficult to cover with conventional liquid coatings, including intricate geometries, narrow gaps and textured surfaces. Liquid paints and protective films may pool, drain or leave uncovered regions when applied to complex objects. A vapour, by contrast, can travel across a surface before condensing, potentially producing a more uniform film. The resulting coating retained the soft, insoluble and hydrophobic characteristics associated with the polymer.

The same process can also remove the coating without solvents or aggressive chemical treatments. When the coated object is reheated to around 90 degrees Celsius, the polymer evaporates from the surface and can, in principle, be captured for reuse. This reversibility could be valuable in manufacturing, electronics, laboratory equipment and other applications where a temporary waterproof or protective layer is needed. A coating might be applied during fabrication, removed during repair, or recovered when a product reaches the end of its useful life. The approach could reduce the need for solvent-based stripping, although the researchers emphasise that practical systems would still need to address energy use, vapour containment, coating thickness and large-scale recovery.

The team also tested whether the polymer could be purified through its unusual phase change. In a model experiment, the material was deliberately contaminated with an additive. Heating caused the polymer to enter the vapour phase while the non-volatile contaminant remained behind. When the vapour cooled, it re-formed as a clean solid. This is a form of purification by sublimation, in which differences in volatility separate one substance from another. Conventional recycling often produces complex mixtures containing dyes, plasticisers, fillers, stabilisers and residues from previous use. The ability to separate a polymer from certain additives without transforming it through multiple liquid chemical stages could provide a useful foundation for future recycling technologies, although the method’s effectiveness will depend on the nature of the contaminant.

The scientists caution that the discovery remains a proof of concept rather than a ready-made industrial solution. A practical replacement for commodity plastics would need to match their low cost, mechanical strength, durability, production volume and resistance to environmental exposure. It would also need to be assessed over many heating and cooling cycles to determine whether the monomer, polymer or coating gradually degrades. Life-cycle studies would be required to compare the energy needed for low-temperature depolymerisation and vapour recovery with the energy used in conventional manufacturing and recycling. Nevertheless, the material’s combination of hydrophobicity, softness, reversibility and relatively low processing temperature suggests that its greatest value may lie not in replacing every plastic, but in inspiring specialised circular materials designed from the outset to be temporary, recoverable and chemically reusable.

The University of Surrey researchers describe the work as the introduction of a new design principle for polymer science: instead of making plastics permanently stable and then struggling to dispose of them, scientists could engineer materials whose stability is deliberately switchable. Touseef Kazmi, the study’s lead author, said the team had demonstrated a principle that was not previously available, while corresponding author Peter Roth said the chemistry could inspire a new generation of circular materials. The next challenge will be tailoring the molecular structure to control properties such as strength, flexibility, evaporation rate and re-polymerisation speed. If those obstacles can be overcome, plastics that vanish into recoverable vapour and return as the same material could turn a dramatic laboratory demonstration into a new route for cleaner coatings, easier maintenance and more precise polymer recycling.

Subject of Research: Reversible, sublimable polymers based on 1,2-dithiolane chemistry for low-temperature depolymerisation, vapour deposition, removable waterproof coatings and polymer purification.

Article Title: Lipoic Acid Without the Side Chain: Sublimable Homopolymers and Degradable Copolymers Based on 1,2-Dithiolane

News Publication Date: 11 August 2026

Web References: https://doi.org/10.1021/acs.macromol.6c01500

References: University of Surrey study published in Macromolecules, DOI: 10.1021/acs.macromol.6c01500

Keywords

Recyclable plastics, polymer chemistry, sublimable polymers, depolymerisation, 1,2-dithiolane, lipoic acid, vapour deposition, waterproof coatings, chemical recycling, circular materials, materials science

Hydrogen embrittlement is a phenomenon that compromises the structural integrity of metals, particularly in the context of high-strength alloys. This has posed a barrier to the utilization of aluminium in crucial applications such as lightweight vehicles and storage tanks for green hydrogen. Until now, researchers have struggled to create alloys that maintain strength while also exhibiting resistance to hydrogen embrittlement. The new research offers a promising solution, setting the stage for aluminium components that are not only strong but also safe for hydrogen applications.

The core of this breakthrough lies in a sophisticated precipitation strategy involving the incorporation of scandium in aluminium-magnesium alloys. This strategy employs a two-step heat treatment process, meticulously engineered to create dual nanoprecipitates within the alloy. The primary nanoprecipitate, Al3Sc, is the first to form, followed by the in-situ development of a shell constituted by a more complex Al3(Mg,Sc)2 phase. This innovative design allows for remarkable distribution of these nanoprecipitates throughout the metal matrix, creating a dual-action effect: the Al3(Mg,Sc)2 phase actively traps hydrogen, while the Al3Sc particles enhance the overall strength of the alloy.

Professor Baptiste Gault, a leading figure in the study, underscores the significance of this dual nanoprecipitate structure in his assertion that the new alloy fundamentally resolves the trade-off between strength and hydrogen resistance that has historically plagued the industry. The results of their investigative work are compelling, revealing a staggering 40% increase in strength and a five-fold enhancement in resistance to hydrogen embrittlement when compared to traditional scandium-free alloys. This dual benefit is anticipated to enable the production of aluminium components that not only meet but exceed current industry standards in automotive and energy applications.

Moreover, the researchers achieved an unprecedented record in tensile elongation under hydrogen-charged conditions. Their tested aluminium alloys exhibited a remarkable elongation of up to 7 ppmw, an indication of enhanced ductility and resilience under hydrogen exposure. Such revelations provide invaluable insights into the atomic-level dynamics of the alloy, with atom probe tomography being instrumental in validating the mechanistic role of the Al3(Mg,Sc)2 phase in hydrogen trapping. The innovative use of advanced microscopy techniques has shed light on the intricate interactions responsible for the alloy’s enhanced properties.

The commitment to translating these laboratory findings into practical applications cannot be overstated. The researchers have rigorously tested their alloy design across multiple aluminium alloy systems, demonstrating its versatility and effectiveness. More importantly, they took significant strides toward scalability, employing water-cooled copper mould casting and thermomechanical processing techniques that align with contemporary industrial practices. This paves the way for a new generation of aluminium materials that not only fulfills the demands of future hydrogen-powered economies but does so safely and effectively.

The collaborative research initiative highlights the importance of international partnerships in addressing complex challenges in material science. Researchers from Xi’an Jiaotong University and Shanghai Jiao Tong University in China contributed significantly to the study. Their collaborative efforts underscore the notion that overcoming scientific barriers often requires a united global approach, pooling resources and expertise to foster innovation and progress.

As the world strives to reduce carbon emissions and transition towards sustainable energy solutions, this novel alloy technology presents an auspicious opportunity for the tree-hugging and tech-savvy communities. By optimizing the properties of aluminium, this research addresses critical industry needs and holds promise for revolutionizing the hydrogen economy. The implications extend beyond materials science; they touch on environmental sustainability, energy independence, and the future of mobility.

In addition to its significance in the hydrogen economy, the development of these advanced aluminium alloys bears relevance to various industries. Lightweight yet strong materials may transform sectors ranging from automotive to aerospace, manufacturing, and infrastructure. Companies that harness the advantages of this research may gain a competitive edge, positioning themselves as leaders in the increasingly important field of sustainable materials.

Looking forward, stakeholders in industry and academia are keen to build upon this foundational research. Further investigations may explore the long-term performance of these alloys in real-world applications, ensuring that advancements in material science translate effectively into commercial performance. As the technology matures, it is expected that adoption rates within industry will accelerate, enhancing the viability of aluminium as a primary material in hydrogen-related technologies.

In conclusion, the development of hydrogen-resistant aluminium alloys represents a watershed moment in material science, one that harmonizes the dual demands of strength and environmental sustainability. The innovative strategies employed by researchers from MPI-SusMat and their partners not only offer exciting potential for the future of hydrogen applications but also signal a new chapter in the quest for sustainable materials. As these findings circulate through the scientific community and industry, their impact is likely to resonate far beyond the laboratory, shaping the trajectory of materials science and engineering for years to come.

Subject of Research: Hydrogen-resistant aluminium alloys
Article Title: Structurally complex phase engineering enables hydrogen-tolerant Al alloys
News Publication Date: 30-Apr-2025
Web References: http://dx.doi.org/10.1038/S41586-025-08879-2
References: Nature
Image Credits: Adapted from: Nature; DOI:10.1038/S41586-025-08879-2

Keywords

Aluminium alloys, hydrogen embrittlement, nanoprecipitates, strength, sustainability, material science, hydrogen economy, atom probe tomography.