Biobased monomers are becoming increasingly important to develop green products to substitute petroleum-based materials [1]. In this study different biobased monomers have been synthesized and exploited both in cationic and radical UV-Curing [2]. Reactivity of curing process was investigated, and the crosslinked materials fully characterized. An easy tailoring of the properties of the final UV-cured coatings is demonstrated by varying the ratio of the monofunctional-difunctional epoxy monomer or by in-situ generation of hybrid organic-inorganic networks. The same formulations were processed in 3D-printing using the hot-lithography technique when processing epoxy monomers [3]. Curing and printability conditions have been defined and the printed object fully characterized. Finally, UV-Cured composites were achieved by exploiting the frontal induced photopolymerization process [4]. This technique allowed to exploit UV-Curing also to achieve thick composites.

Additive manufacturing (AM), also known as three-dimensional (3D) printing, is a fabrication technique for products of high customization regarding their size, shape, and design. Guided by Computer Aided Design (CAD) software, objects are printed layer by layer, achieving accuracy and significantly less waste material compared to traditional processing techniques.
UV curable resins utilized in VAT photopolymerization 3D printing, mainly comprise of acrylic acid based polyesters and polyurethanes. However, acrylic acid based materials possess allergenic and irritation potential, can be volatile and toxic, especially at low molecular weights, while also not typically being produced from renewable resources. Furthermore, this type of 3D printed materials are often non-recyclable, ending in the waste streams after their end of life. Therefore, it becomes clear that alternative biobased and recyclable resins, are of high interest.
We have developed unsaturated polyester resins, of high biobased content, and studied their properties and printability with a digital light processing (DLP) 3D printer. To this end, monomers from renewable resources were utilized for the synthesis of the polyesters, including itaconic acid, succinic acid and 1,3-propanediol. The produced resins were evaluated regarding their photopolymerization and physicochemical properties and the materials produced via 3D printing were characterized for their thermomechanical properties. To facilitate mechanical recycling of the printed parts, dynamic disulfide bonds were introduced into the structure of the prepared polyesters. The reprocessability and properties of the materials after thermal reprocessing were also evaluated.

Acknowledgments
The research work was supported by the Olle Engkvists Stiftelse (Fellowship Registration Number: C-2023-2369).

The creation of functional and sustainable materials for additive manufacturing is an increasingly growing field of interest. In this context, composite blends of chitosan, including both commercially available low and medium molecular weight variants and laboratory-extracted chitosan from shrimp head and shell waste, were fabricated with polylactic acid (PLA) using extrusion molding. Filament characterization was performed to investigate the impact of chitosan molecular weight and content on filament properties, utilizing melt flow index, tensile testing, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). The morphology of the extruded filaments was examined using scanning electron microscopy (SEM). Furthermore, the feasibility of incorporating a high metal content into the composite filaments without compromising their printability and structural integrity was explored. The findings revealed that specific chitosan-PLA composite filament compositions allow for the successful integration of nickel, underscoring their potential as innovative catalyst supports. The filaments were 3D-printed by Fused deposition modelling (FDM), and the resulting specimens were subsequently analyzed using micro-CT. This approach strives to create an innovative material from food waste, offering a sustainable and circular solution for transforming seafood waste into advanced functional materials. The successful incorporation of shrimp waste-derived chitosan into PLA filaments not only improves material properties but also showcases the potential for generating high-value products from bio-waste. This contributes to environmental sustainability and advances the field of eco-friendly additive manufacturing. This study emphasizes the promising applications of composite filaments in multiple industrial sectors, showcasing their role in supporting a circular economy.

Photopolymerisation-based 3D printing, such as digital light processing (DLP), has the potential to be a greener method of fabricating polymer materials. However, there have been few advancements in the chemistry of commercial photoresins in the 40 years since the invention of DLP printing. Therefore, parts printed by this method are non-recyclable and non-degradable, preventing 3D printing from becoming a wholly sustainable technology. In an ideal system, printed photopolymers are designed to be either depolymerisable or degradable in the environment. In order to achieve this, new chemical approaches must be applied to the design of photopolymer systems.
In this work, we aim to design degradable and circular photoresins for DLP printing. This presentation will explore approaches to improving the end-of-life sustainability of DLP resins, focussing on the design of photodegradable materials that degrade completely to small molecules, and chemically circular photopolymers via the incorporation of dynamic covalent bonds, while optimising mechanical performance and printing quality.

Sustainable energy resources require advanced solutions, and triboelectric nanogenerators (TENGs) have a lot of potential.¹ However, their environmental advantages are compromised by their dependency on energy-intensive production techniques and petrochemical polymers.² In this study we demonstrate a bio-derived approach to overcoming these challenges by developing high-performance TENGs through material optimization and advanced manufacturing techniques.
UV-crosslinked formulations based on functionalized rapeseed and soybean oils combined with isobornyl acrylate were tailored to enhance triboelectric charging. The coatings produced up to 250 V of generated voltage by surface structuring and formulation adjustments, which is a 25-fold gain over unmodified systems. Additionally, these materials are degradable by alkaline hydrolysis, guaranteeing environmentally friendly disposal methods.
To further advance this technology, the optimized formulations were used for dual-head 3D printing, enabling the fabrication of mechanically distinct and complex TENG structures. By removing the requirement for internal electrodes and greatly improving electromechanical response, dual-head 3D printing approach allowed to achieve performance that was remarkably higher than for single-polymer design. The resulting 3D-printed devices demonstrate superior energy harvesting efficiency and expand the functional versatility of plant-derived TENGs.
The demonstrated approaches show a scalable pathway for developing sustainable energy solutions, leveraging bio-derived materials for coatings and advanced 3D structures to maximize performance and environmental compatibility.

Despite significant progress, fabricating complex hydrogel structures with high resolution and good mechanical integrity remains challenging due to their inherent softness, high water content, and time-consuming processing. In contrast to traditional layer-by-layer methods used in conventional fabrication technologies, volumetric printing (VP), a state-of-the-art additive manufacturing (AM) technology, can rapidly produce entire 3D structures in seconds within the volume of a rotating vial.[1-4] In this work, multi-functional poly(ethylene glycol) (PEG) building blocks are employed to construct hydrogel scaffolds using the uniform photo-induced step-growth thiol-norbornene (NB) reaction. The rapid gelation kinetics and high selectivity of this chemistry make it an ideal biomaterial ink for light-based AM technologies, particularly VP. We demonstrate that thiol-NB chemistry with a well-defined backbone enables fast fabrication of complex and robust geometries via VP in less than 35 seconds without tedious post-curing/post-processing. This unique combination of speed, design freedom, and robust mechanics expands the potential for fabricating patient-customized hydrogel structures for tissue engineering applications.