Cationic photopolymerization offers a significant advantage over radical polymerization due to its resistance to oxygen inhibition and superior dimensional stability during crosslinking process. Here we advanced the development of bio-based monomers for cationic photopolymerization by synthesizing oxetane-functionalized derivatives of adipic and itaconic acids. These renewable acids were chosen for their multifunctionality and availability. The synthesized monomers, bis((3-methyloxetan-3-yl)methyl) adipate (BOA) and bis((3-methyloxetane-3-yl)methyl) itaconate (BOI), were fully characterized using nuclear magnetic resonance (NMR) spectroscopy. Fourier transform infrared (FTIR) spectroscopy and photo differential scanning calorimetry (photo-DSC) were employed to monitor the oxetane ring-opening reaction kinetics and to determine the degree of conversion, revealing high reactivity for both monomers, reaching nearly complete conversion within 90 seconds. The properties of the UV-cured films were assessed by dynamic mechanical thermal analysis (DMTA), and gel content measurements. Results indicated that the BOI-based films exhibited higher glass transition temperatures (Tg), and crosslinking densities compared to BOA-based films, which is explained by the shorter length and higher functionality of itaconic acid provided by the incorporated double bond. The findings demonstrate the potential of bio-based oxetane monomers to produce UV-curable materials with acceptable thermomechanical properties, paving the way for more sustainable alternatives to petroleum-derived precursors.

The increasing demand for sustainable materials has driven the exploration of renewable monomers in polymer synthesis. Syringaldehyde methacrylate (SyMA), a lignin-derived, is a promising bio-based substitute for styrenic derivatives in acrylate copolymers, with potential applications in many field [1][2].
In this study, SyMA was copolymerized with butyl acrylate (BuAc) using ARGET-ATRP, a controlled radical polymerization technique (Figure 1). [3]
Polymerization conditions were optimized by evaluating the effects of three ligands of Cu(II): PMDETA, Me6TREN, BiPy, and of three initiators such as EBiB, EBPA, TsCl. Optimal conditions were determined to be SyMA/BuAc/CuBr₂/Me6TREN/EBiB/Sn(oct)₂ at a molar ratio of 1000/1000/1/1/10/80 at 90°C in toluene, yielding 71% after 24 h. A comparable ARGET-ATRP of styrene/BuAc (1:1) at 90°C reached 86% conversion after 24h [4].
Copolymers of varying SyMA/BuAc compositions were characterized via ¹H-NMR, TGA, DSC and GPC. Glass transition temperature (Tg) varied with composition according to the Flory-Fox equation and the thermal degradation temperature increased with increasing the BuAc (Figure 2).
A P(SyMA-ran-BuAc) copolymer with 55 wt% of SyMA exhibited a Tg of 64°C, significantly higher than the Tg of 34°C observed for a styrene-BuAc copolymer with 55 wt% of styrene. [5]
Kinetic studies carried out by ¹H-NMR spectroscopy and GPC analyses revealed a linear conversion trend, confirming the controlled polymerization (Figure 3). [3]
Films prepared from these copolymers showed significant stretchability but permanent deformation post-extension.
These findings demonstrate the possibility of replacing styrenic monomers with SyMA, offering a sustainable pathway to polymeric materials with adjustable thermal and mechanical properties.

Bio-based vanillin from lignin is a relevant building block for a plethora of green polymer concepts. It provides a lower CO₂ footprint compared to synthetic vanillin and is potentially scalable. Here we explore bio-based polyether concepts based on dehydrovanillin. The synthesis of dehydrovanillin can be performed through a known enzymatic pathway using laccase [1]. The two Cα carbonyls in dehydrovanillin, were reduced to hydroxyl functional groups using NaBH₄ in ethanol with acidic workup. The formed hydroxyl groups potentially undergo a hypothesized polycondensation with primary and secondary alcohols forming a polyether. These polymers have the potential to be chemically recyclable and dynamic. From current results the reduction was successful and the polycondensation of the reduced was found to yield small oligomers. Despite optimal polymerization conditions yet to be found, here we show intriguing new polymer concepts using dehydrovanillin.

In the pursuit of sustainable and bio-based materials with reduced environmental impact, polycondensation reactions have emerged as a promising method for producing thermosetting polyesters from renewable natural building blocks. Unlike traditional polymer resins such as epoxy and polyurethane resins, which often exhibit toxic properties due to their use of highly reactive functional groups (like epoxides and isocyanates), polycondensation-based resins offer a safer alternative. The polycondensation reactions, often involving multifunctional carboxylic acids and alcohols, typically proceed under milder conditions and do not rely on such reactive, hazardous components. As a result, polycondensation-based bio-resins have the potential to reduce the toxicological risks and environmental impact that are common with petrochemical-derived materials.
This study presents the synthesis and characterization of bio-based polyester foams derived from multifunctional carboxylic acids, including succinic acid, glutaric acid, and adipic acid, in combination with multifunctional alcohols such as trimethylolpropane and pentaerythritol. By carefully selecting and adjusting these raw materials, the kinetics of the different materials were calculated and material properties were tailored to meet specific performance requirements.
The presentation will demonstrate the versatility of a modular system for creating bio-based foamed polyesters with a wide range of customizable properties, from soft, elastic foams to rigid, stable structures. By controlling the choice of reactants and reaction conditions, these foams present a sustainable alternative to traditional petrochemical-based materials. They offer a solution to reduce environmental and toxicity concerns while maintaining desirable mechanical and thermal properties, making them suitable for diverse applications across industries.

Aliphatic polyesters featuring long methylene repeating units combine biodegradability with enhanced physical properties like high melting points, rapid crystallization, thermal stability and mechanical strength, resembling polyethylene-like characteristics.(1) Early pioneers such as Carothers, established a foundation for groundbreaking research on polyester synthetic fibers based on linear hexadecanedioic acid and propanediol.(2) In the decades that followed, long-chain polycondensates have received limited attention because of the restricted availability of suitable monomers. Recently, these materials have regained interest as corresponding monomers have become more available, alongside environmental concerns associated with petroleum-based materials and plastic waste management. Despite their potential, their synthetic technique typically requires high reaction temperatures (150–280°C) and toxic heavy metal catalysts. Solvent-free enzyme-catalyzed polycondensation, particularly using immobilized Candida antarctica lipase B (iCALB), have emerged as green alternatives to traditional metal-based catalyzed polymerizations, aligning well with green chemistry principles through milder conditions and high efficiency.(3) Therefore, enzyme-catalyzed melt polycondensation of biobased aliphatic polyesters, is of significant interest. Novel biobased short-chain diols, such as 1,4-butanediol, along with medium- and long-chain length biobased diacids are used to produce aliphatic polyesters in this research. The key variables such as the enzyme concentration, reaction time and temperature were optimized to maximize yields and control molecular weights of the final products. The chemical structures were verified by 1H, 13C and 2D nuclear magnetic resonance (NMR) analyses and size exclusion chromatography (SEC) was used to determine the molecular weight. The thermal behavior of the polyesters was analyzed via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Green chemical modification of cellulose presents a unique challenge, particularly from the perspective of sustainable development. Many strategies commonly used in polymer chemistry cannot be directly transposed to this essential biopolymer in the search for alternatives to fossil-based materials. The absence of simple and environmentally friendly solvents for cellulose processing forces us to change our paradigm.
A more desirable strategy would involve working under heterogeneous conditions, utilizing readily available cellulose sources, such as wood or wood fibers, that do not require extensive processing and, of course, use non-hazardous reactants and solvents of biobased relevance.
This framework has been the guiding principle of this PhD project, which first focused on developing a novel bio-based reactivity promoter for heterogeneous reactions (improving chemical accessibility of cellulose). [1] The methodology was then further extended to other relevant bio-based anhydrides. [2] Finally, fine-tuning cellulose chemistry through this approach enabled us to explore new material design concepts, ranging from ultra-charged fibers for water remediation to innovative, high-strength wood plastics.

Coffee is one of the world’s most popular beverages, generating 9,000 tonnes of spent coffee grounds (SCG) daily in Europe. The production of 1 kg of coffee releases 17 kg of CO₂, making SCG both an environmental challenge and a potential recycling resource. Recycling SCG helps reduce CO₂ emissions, supporting decarbonization in the coffee and chemical industries.

Coffee oil, which makes up 15-30% of SCG by weight, is rich in fatty acids and has primarily been used for biodiesel production. However, using coffee oil solely for combustion is inefficient due to its high value. This study explores its potential as a raw material for polymer production.

Coffee oil fats provide a carbon source for microbial growth. Under low nitrogen and phosphorus conditions, certain bacteria produce polyhydroxyalkanoates (PHAs), which are biodegradable and biocompatible, making them suitable for biomedical and packaging applications.

This research investigates the microbial production of polyhydroxybutyrate (PHB) using Cupriavidus necator. Bacteria were cultured in a mineral medium with coffee oil as the carbon source. The PHB content was analyzed via gas chromatography and 1H NMR confirmed the polymer’s structure. The study compared batch and fed-batch cultivation modes, finding that fed-batch mode resulted in 2.9 g/l higher PHB after 48 hours. The carbon-to-nitrogen (C/N) ratio also influenced PHB production, with higher coffee oil concentrations increasing the yield. Optimal conditions produced PHB with a molar mass of 550 kg/mol, determined by gel permeation chromatography (GPC).

From automobiles and marine craft to construction materials, unsaturated polyester resins (UPRs) are widely utilized in different parts of the composite industry. Green alternatives to fossil-based monomers have been studied extensively in the polymer industry, but due to high price and low availability, furan-based high-performance monomers have been considered less commercially competitive to be utilized in UPR applications. As the cost of raw materials is starting to decrease and recently made studies with 2,5-furandicarboxylic acid (FDCA) have shown potential, conducting further studies on biobased furans is worthwhile.
In this study, novel unsaturated polyesters were made via melt polycondensation from furfural-derived monomer, unsaturated diester monomer, and a mixture of diols. After curing with a reactive diluent, thermal and mechanical properties of the resins were studied, showing excellent results with the most optimal diol composition. The new resin showed a high glass transition temperature of ca. 100 °C. Additionally, it was found through tensile tests that higher tensile strength, E modulus, and strain were demonstrated by the resin when compared to a commercial fossil-based analogue. Our promising results on the novel UPR indicate potential for improved performance characteristics in various applications. Future research will focus on studying the compatibility of the resin with commonly used fibres and its usability in fiber-reinforced composite applications.

The growing environmental awareness by institutions and governments has encouraged the development of sustainable alternatives to fossil-based polymeric materials [1]. Bio-based substrates have the potential to provide sustainable alternatives for the polymer industry, and their higher degree of functionalization compared to petrochemical analogues opens up possibilities for alternative applications [2].
4-vinyl guaiacol acetate (4-VG-Ac), a renewable styrene type monomer, was produced from vanillin in a telescoping reaction, allowing satisfactory yields and a straightforward single purification step. The monomer bears much synthetic potential, as a simple post-polymerization deprotection step would allow for pending phenyl groups to be exploited for post-functionalization [3].
4-VG-Ac was then tested towards Atom Transfer Radical Polymerization (ATRP), achieving good monomer conversion and control in its Supplementary Activator and Reducing Agent (SARA) variant.
Optimization required the evaluation of various reaction parameters and their effect on the polymerization system, leading to optimal choice of solvent, catalytic system and initiator. In particular, the use of highly active chloride-based ATRP initiators and CuCl2/TMPA catalytic system played a major role in establishing control over the polymerization.
The polymers produced by SARA ATRP exhibit excellent control over molecular weight and dispersity and good initiation efficiency values. However, early termination due to dehydrohalo-genation poses a severe limitation to the reaction system, allowing satisfactory monomer conversion values only at low target degrees of polymerization. Further studies will be necessary to extend the scope of monomer application to different polymer architectures and develop its synthetic potential once a deprotection step is performed.

Synthetic polymeric materials are indispensable in modern day life due to their versatility and performance. However, popular synthetic polymeric materials are often derived from fossil sources and their biodegradability is poor. Indeed, when these materials end up in nature they are typically persistent, since biodegradation does not occur at a relevant timescale, leading to a buildup of (micro)plastics and leachables that pollute ecosystems.[1,2] In order to properly deal with this, designing novel synthetic polymeric materials that are intrinsically biodegradable within an acceptable timeframe is essential. Unfortunately, most commercial biodegradable synthetic polymeric materials often exhibit poor thermal and/or mechanical properties, limiting their performance compared to conventional materials.[2]
We recently published on a novel tricyclic lactone derived from biomass via Diels-Alder chemistry affording a chemically recyclable, high glass-transition temperature polymer from ring-opening polymerization (ROP).[3] Building upon this work, we set out to increase polymer polarity to systematically study the influence of increasing polymer polarity on (bio)degradation rates. Epoxidation of the tricyclic lactone leads to a novel monomer that can undergo controlled ROP to yield a polymer that is chemically recyclable and also undergoes facile hydrolysis under mildly acidic or basic conditions. Simultaneously, it exhibits a high glass-transition temperature of 197 °C and a 10% degradation temperature of 250 °C. The same polymer can be obtained by post-polymerization modification of the previously-reported polymer. Copolymers can be synthesized via concurrent polymerization of both lactones, resulting in gradient copolymers, or through post-polymerization modification, resulting in random copolymers.

CO2 based polymers have attracted a significant attention in recent times. CO2, being a naturally abundant, non-toxic, and low-cost renewable resource, makes it a relevant starting material. Polycarbonates are a class of polymers synthesized via ring-opening copolymerization (ROCOP) of CO2 and epoxides.1 These are an alternative to long-established fossil-derived, non-degradable polymers, that help dealing with current environmental concerns, reducing the heavy reliance on fossil-fuels, and establishing a greener and more sustainable future. These versatile polymers generally have desirable features like hardness, longevity, degradation, lightness, and durability against heat, which makes them potential candidates as single-use plastics, packaging, and in the biomedical fields.2
We will present the outcome of our attempts in designing a series of unprecedented functional ter- and quater-polymers upon exploring metal-free catalyzed ROCOP of CO2 with different epoxides and anhydrides.3 Choice of the epoxide was made considering the extra functionality of the monomer which could be exploited for post-polymerization modification. Variation of the (co)monomer(s) nature and initial loading provides polymers with tunable compositions in each component, featuring distinct properties.4 In particular, a range of valuable macromolecular, thermal and mechanical properties, resulting in diversified applications, are expected. Our latest advances will be discussed.

Due to the ongoing depletion of fossil resources, the use of renewable feedstock for the development of new chemical processes has received increasing attention in recent times. In this context, vegetable oils provide a platform for long, unbranched aliphatic chains containing carbon-carbon double bonds, the latter of which offer rich opportunities for further chemical transformations. Herein, we present a novel synthetic strategy to convert the double bonds of high oleic sunflower oil (HOSO) into secondary thiol functions via combination of a catalytic ester reduction method and thiol-ene click chemistry. Due to the trifunctional nature of HOSO and its high content of monounsaturated fatty acids (>85%), a polythiol with >2 thiol functions per molecule is obtained. The methodology is further extended to an artificially synthesized triglyceride of bio-based 10-undecenoic acid, which can be obtained from castor oil, allowing the synthesis of a primary polythiol. Both polythiols have been successfully employed as crosslinking agents for the synthesis of thiol-ene networks.

The increasing interest in reducing the dependence on fossil-based resources by searching and replacing them with renewable biobased sources has intensified in both academic and industrial sectors. To date, hemicellulose-derived furfural has received rather minor attention, compared to 5-(hydroxymethyl)furfural, even though recent studies show various excellent results in applications especially utilizing furfural. The purpose of the research was to synthesize two novel epoxy resins from furfural and utilize them in biobased composites conducting comparative studies with commercially available and widely used fossil-based epoxy resin, diglycidyl ether of bisphenol A (DGEBA).¹ Resins were cured with methylhexahydrophthalic anhydride with optimized amounts of 2-ethyl-4-methylimidazole initiator. For the resins comprehensive curing behavior, thermomechanical, thermal stability, water absorption, and tensile properties, including adhesion strengths were evaluated in detail. Novel sulfur-bridged furfural-derived epoxy resins were synthesized successfully with high yield and purity. The carbon content in these bioresins can fully originate from lignocellulose-based biomass sources, since all of the carbon containing starting materials can be produced from biomass. Mechanical analysis shows superior tensile strengths for the cured bioresins compared to conventional DGEBA, and the same trend can be seen with single-lap joint adhesion tensile tests. All the cured epoxy systems exhibited good thermal stability. As presumed water absorptions of the cured bioresins were slightly higher, due to the hydrogen bonding of the hydroxyl groups. In conclusion, the synthesized bioresins have great potential to be able to replace DGEBA in various applications.

The crosslinking of LDPE was studied during melt processing using dynamic (dicyclopentadienoic acid bisTEMPO ester – Image A) and conventional (adipic acid bisTEMPO ester) crosslinking agents1. The concentration of both crosslinking agents was varied from 1.45 to 5.8 mol%. The crosslinked samples were thermally treated (160 °C, 20 min) and dissolved in hot xylene. Compared to pure LDPE, the dynamically cross-linked LDPE showed no change in the soluble fraction, indicating the decomposition of the crosslinks, while the conventionally crosslinked LDPE showed a decrease in the soluble fraction with increasing crosslinker concentration. The viscosity as a function of shear stress for the two type of crosslinked samples at 130 °C showed only slight differences, while the values for pure LDPE were significantly lower (Image B). At 170 °C, the viscosity values of dynamically crosslinked LDPE were lower than those of conventionally crosslinked LDPE, indicating the break-up of the dynamic crosslinks (Image C). Similarly, at 170 °C, the shift of the stress release curve of dynamically crosslinked LDPE towards the curve of pure LDPE was observed and explained by the cleavage of the dynamic moieties. The mechanical properties of crosslinked LDPEs showed an increase of the Young's modulus and tensile strength (9-10.5%) and a decrease in elongation at break compared to pure LDPE when the concentration of the two cross-linkers was increased. The creep tests also showed a decrease when the concentration of both crosslinkers increased, thus confirming the crosslinking of LDPE.

Thermosetting polymers are widely used due to their excellent thermomechanical properties. However, their recycling remains a significant challenge because of the irreversible covalent crosslinking within their network. To address this issue, considerable research efforts have been dedicated to designing chemical networks with reversible and/or dynamic cross-links. Despite these advancements, the development of vitrimer polyolefins remains largely unexplored. One promising approach for creating vitrimer polyethylene (PEV) involves the Diels–Alder (DA) reaction, which enables thermal reversibility through the retro Diels–Alder (rDA) reaction between diene and dienophile pairs. In this study, specific derivatives of allyl furan and bismaleimide were synthesized as diene/dienophile adducts. High-density polyethylene (HDPE) was then grafted with allyl furan and crosslinked with bismaleimide using a twin-screw extruder, resulting in a thermally reversible PEV. To evaluate its vitrimer properties, a frequency sweep test was conducted to determine the gelation point, confirming gel formation. Also, additional mechanical tests, including dynamic mechanical analysis (DMA) and tensile testing, were performed for further characterization. Notably, PEV demonstrated the ability to reform after being cut and heated at 150 °C for 45 minutes, highlighting its recyclability potential.

We investigate the suitability of vitrimers based on poly(dimethyl siloxane) (PDMS) as electrical insulating materials for applications in high-voltage engineering.
Vitrimers are a class of polymer materials that combine properties of both thermoplastic and thermoset polymers. They possess dynamic covalent bonds that can reorganize upon heating, making them recyclable, repairable, and adaptable. They are therefore promising materials for a sustainable and resource-efficient circular economy. Many systems have been reported in the last years, originating from many different laboratories. Often, only the characteristics of the materials as such are reported, e.g. mechanical properties or reshaping properties.
PDMS materials are common insulators in high-voltage engineering due to their excellent mechanical and electrical properties, e.g. their high resistance against electrical damage. So far, there are little reports on the influence of the exact PDMS network chemistry on its electrical properties. Hence, we focus on the question whether a strongly modified network structure (as needed for the synthesis of PDMS vitrimers) does influence the dielectric properties of the materials, and if yes: to which amount. Pure PDMS materials, that is silicone networks without any fillers but a finely controlled composition that are based on the crosslinking of vinyl terminated PDMS with tetrakis(dimethylsiloxy)silane via platinum catalyzed hydrosilylation reaction [1] are compared with PDMS vitrimer systems based on polyesters[2] or vinylogous urethanes[3]. First results will be presented.

This study explores the structural evolution of lignin-derived supramolecular polymers within covalent adaptable networks (CANs) using in-situ small- and wide-angle X-ray scattering (SAXS and WAXS). CANs, a promising class of reconfigurable materials, rely on dynamic crosslinking to enable recyclability and mechanical adaptability.1–3 SAXS is employed to track nanoscale changes in network topology, including the rearrangement of crosslink domains during mechanical deformation and thermal reprocessing. Simultaneously, WAXS is employed to investigate molecular packing, capturing interchain distance variations and local structural ordering within the adaptable matrix.
Temperature-resolved SAXS/WAXS data provide a detailed understanding of how network morphology evolves under thermal cycling and provide key observations on how lignin-derived CANs exhibit tunable structural dynamics, enabling self-healing and stress relaxation while maintaining mechanical performance.4 These insights are crucial for optimizing material design, ensuring recyclability and sustainability in applications such as recyclable coatings, self-healing polymers, and high-performance composites. This work bridges fundamental structure-property relationships with practical applications, contributing to the advancement of circular polymer systems for sustainable material innovation.

Low-density Polyethylene (LDPE) is a widely used thermoplastic polymer in various industries due to its versatility and cost-effectiveness. Upon crosslinking, XLPE is formed, a material used for instance in insulation cables due to its good resistance to heat and high voltage electricity. We recently developed a LDPE ionomer based on ion pair comonomers (IPC) that can extend the range of application where traditional LDPE are limited. Such ionomers are produced directly in the reactor, without any neutralization step which is typically used in incumbent technologies. They feature a crystallinity, melting temperature, rubber plateau modulus and thermal conductivity close to XLPE but remain melt-processable. Moreover, the preparation of such ionomers is free of byproducts. As a result, such ionomers can be used in a variety of applications, including areas where both crosslinked structure and melt processability are required.