Epoxy-amine polymerisation has been a corner-stone technology of the coating, composites and adhesives industries for over 80 years. With a vast range of epoxy resins and aliphatic amines available on a commercial scale, advanced materials such as depolymerizable network polymers, recyclable/repairable composites and novel approaches to low-temperature cure powder coatings are attractive propositions from a scale, cost and implementation perspective.
Epoxy-amine-dioxazaborocane (EAD) chemistry exploits this rich source of structurally diverse monomers in new and exciting ways, to deliver industrially relevant polymeric materials for a range of applications. Epoxy resins and aliphatic amines can be co-polymerised and cross-linked with diboronic esters to form dioxazaborocane network polymers. This approach exploits not only these useful building blocks but also utilises the -amino diol functionalities created during the co-polymerisation process, to form hydrolytically robust, ‘multi-chelate’ crosslinking bonds with a rigid 5,5-fused bicyclic (dioxazaborocane) structure. The result is a diverse and versatile co-polymerisation process that can deliver network polymers with a range of useful properties, including very high Tg network polymers suitable for powder coating applications and engineering plastics. This class of EAD network polymers also exploits an integrated mild and chemoselective depolymerisation process which allows recovery of both polymer and other materials in excellent condition.
Finally, we also report that EAD covalent adaptable networks can be used to create thermoset (storage stable) powders that exploit ‘vitrimer flow’ as a mechanism for particle coalescence and film formation on application of heat, including a study of structure-property relationships for this application.

In 1965, DuPont research scientist Stephanie Kwolek discovered that poly(p-phenylene terephthalamide) (PPTA) can be dissolved into a liquid crystalline solution and spun into ultrahigh modulus aramid fibers, which are now known commercially as Twaron or Kevlar. The excellent properties of aramid fibers have led to their widespread use in various advanced applications, including ropes and cables, high-performance fabrics, advanced composites, and ballistic armor [1]. Regrettably, these advantageous properties also pose significant challenges to the closed-loop recycling of aramid fibers. While postindustrial waste aramid fibers can undergo mechanical recycling, where they are chopped into pulp, the resulting materials typically exhibit relatively low economic value (i.e., downcycling) and are not recycled after their use [2]. Chemical recycling, however, enables the production of virgin-quality polymers from polymeric waste through depolymerization followed by purification and repolymerization.

Therefore, we investigated the microwave-assisted depolymerization of PPTA [3]. The alkaline hydrolysis of PPTA was conducted in a microwave reactor at temperatures ranging from 240 to 260 °C with reaction times of 1–15 minutes. The highest conversion (96%) was found after 15 minutes at 260 °C. The resulting monomers terephthalic acid and p-phenylene diamine were successfully purified (>99% purity) in good yields via extraction and precipitation methods. The results of this study present the fastest depolymerization of PPTA to date under relatively mild conditions, thereby encouraging a circular value chain for PPTA.

Monomers derived from renewable resources, such as plant oils, have received increasing importance recently as source for polymer manufacturing.[1] Soluble polymers are obtained from monomers comprising either one epoxy group using cationic polymerization or one methacrylate group using free radical polymerization although crosslinked polymers are received from monomers containing two or more polymerizable functional groups.[2-5] From a broad variety of various plant oils, cotton seed oil appears interesting because it does not belong to the food chain. Therefore, cotton seed oil was selected for synthesis of both the epoxy monomer by epoxidation of the double bounds containing in the cotton seed oil and methacrylate monomer by ring opening reaction of the epoxy groups containing in the epoxidized cotton seed oil with methacrylic acid.
Photo-DSC and real-time FT-IR measurements show quantitative conversion of the methacrylate groups during free radical polymerization of the methacrylated cotton seed oil within less than 5 min. However, the glass transition temperature of the crosslinked polymethacrylate film is low caused by the high content on aliphatic structures. Crosslinking of the methacrylated cotton seed oil in the presence of an aromatic compound results in an increase in the glass transition temperature of the crosslinked films.
Furthermore, addition of an aromatic compound during photoinitiated polymerization affects the polymerization kinetics in case of both methacrylated cotton seed oil and epoxidized cotton seed oil as shown by photo-DSC and DMA investigation. Moreover, crosslink density of the polymer films is influenced by the aromatic compounds as well.

In response to the pressing need for finding sustainable alternatives to petroleum-based epoxy resins, this study introduces a novel approach to developing high-performance, bio-based thermosets with enhanced recyclability. Utilizing lignin-derived precursors, vanillin and syringaldehyde, we synthesized Schiff-base monomers that were subsequently glycidylated to create innovative epoxy resins. A key advancement in this research is the successful self-polymerization of these bio-based epoxy monomers without useing additional curing agents, marking a significant step forward in green chemistry approaches to thermoset materials [1, 2].
The resulting Schiff-based epoxy thermosets exhibit remarkable thermo-mechanical properties, surpassing those of traditional DGEBA-based systems. Glass transition values range from 138 °C to 249 °C, with storage moduli at room temperature between 1.5 and 2.2 GPa. These materials demonstrate excellent thermal stability, with T5% values of 310-350°C in air. Notably, the thermosets show inherent flame retardancy, achieving Limiting Oxygen Index (LOI) values of 33-36% without additional flame-retardant additives [3].
A distinguishing feature of these bio-based thermosets is their low apparent density ~0.74-1.09 g/cm³ compared to DGEBA references, making them ideal for lightweight structural applications. Furthermore, the incorporation of dynamic imine bonds enables both thermal reprocessing and chemical recycling in acidic conditions, addressing crucial end-of-life considerations.
By combining mechanical properties, thermal stability, and recyclability, these novel thermosets represent a significant advancement in the development of environmentally friendly alternatives to traditional epoxy resins.
Keywords: Bio-based thermosets, Schiff bases, High-performance, Dynamic linkage
Acknowledgements:
The authors are grateful to Air Force Office of Scientific Research for funding this research by the grant FA8655-23-1-7024.

Composite materials display many advantages over traditional materials, whether in terms of lightness or mechanical and chemical resistance. In a context of sustainable development, a growing number of works relate to the production of composites with bio-based matrices including polylactide (PLA), which has become a major actor in the market which could in the long term serve as an alternative to petroleum-based polyolefins.[1] Among the various composites production processes, Resin Transfer Molding (RTM) is a specific process which relies on the injection, into a mold containing fibers, of a monomer and a catalyst in order to carry out the in situ polymerization of the matrix. The major advantage over conventional melt processes is the possibility of reaching a high amount of fibers while improving their wetting by the matrix. While a wide selection of thermosetting matrix resins are available on the market for RTM process, there are only a few commercial resins for thermoplastic matrices (TP-RTM).[2]
Although composites production has been reported with E-caprolactone (E-CL) in TP-RTM,[2] PLLA-matrix composites via this process had never been described. Recent studies made it possible to obtain the first PLLA/glass fiber composites prototypes.[3a] We present here current work aiming at strengthening the mechanical properties of the PLLA matrix by producing a novel composites family by copolymerization of L-LA with E-CL (PLCL), with various reinforcements.[3b] PLCL/glass fabric prototype with 30 % E-CL displays an impact resistance 87% higher than pure PLLA analog. PLLA-matrix composites with natural fibers were also produced via this process.[4]

This study investigates the synthesis and application of betulin dioleate epoxide (BOE) as a bio-based
building block for epoxy resin formulations. Derived from betulin, a naturally occurring triterpenoid,
BOE combines renewable resource origin with the functional versatility of epoxides, addressing
environmental and sustainability challenges in the coatings industry [1] . The research integrates BOE
with epoxidized rapeseed oil (ERO) to develop a novel epoxy system with enhanced mechanical,
thermal, and chemical properties. [2]
The synthesis involved two steps: esterification of betulin with oleic acid, followed by epoxidation to
form BOE. Extensive characterization using FTIR, NMR, TGA, and DSC confirmed the chemical
structure and thermal properties of BOE. Curing behavior was evaluated using anhydride-based
hardeners, revealing BOE’s limited self-curing ability due to steric hindrance, but excellent
performance as a hardening additive in mixed systems. [3]
Compositions incorporating BOE and ERO exhibited tunable mechanical properties, balancing rigidity
and flexibility, and were optimized through varying ratios. Rheological studies demonstrated longer
gel times and higher activation energies for BOE-rich systems, highlighting the slower curing kinetics.
The resulting bio-based epoxy coatings showed promising thermal stability (IDT > 290°C) and high
curing efficiency (epoxide conversion up to 92%), with potential applications in eco-friendly coatings
and composites.
This work underscores the potential of betulin-derived epoxides in advancing sustainable material
science, contributing to reduced environmental impact while meeting performance demands of
modern industries. Future research will focus on scalability and broader applications of this
innovative bio-based material.