Bio based photocurable polymers for advanced applications

This doctoral thesis investigates the development of sustainable, functional, and photo-curable materials based on waste-derived cellulose, addressing the environmental and sustainability challenges associated with conventional fossil-based polymers. Cellulose, the most abundant natural polymer, was selected as a renewable feedstock due to its availability, structural versatility, and chemical functionality, and was integrated into photocurable systems and additive manufacturing technologies. The first part of the thesis introduces the fundamentals of photopolymerization, photocurable polymer systems, and their role in additive manufacturing, with a focus on the challenges and opportunities related to bio-based and smart materials. Two complementary extraction and purification strategies were developed to valorize agro-industrial waste into distinct cellulose-based materials: a mild process yielding a cellulose-rich pulp with a lower degree of purification, and a selective route producing microcrystalline cellulose with properties comparable to commercial grades. These materials served as the basis for subsequent material design strategies. Cellulose was employed as an active component in three different functional photocurable platforms. First, a flexible, ionically conductive strain sensor was developed using waste-derived cellulose pulp from olive leaves dispersed in a photopolymerizable deep eutectic solvent, enabling simultaneous functionalization and crosslinking. The resulting formulation was compatible with DLP-based 3D printing and produced soft, highly deformable materials with stable and efficient strain-sensing performance. In addition, a fully cellulose-based fluorescent sensing platform was developed for the selective detection of hazardous volatile organic compounds. Microcrystalline cellulose was functionalized with fluorescent naphthalimide moieties, yielding self-standing sensors responsive to formaldehyde and hydrogen sulfide in both gaseous and aqueous environments. The feasibility of using waste-derived cellulose obtained through selective purification was also demonstrated. Finally, a bio-based vitrimeric photopolymer resin was developed to overcome the recyclability limitations of conventional thermosets. Methacrylated microcrystalline cellulose extracted from aloe vera peel was used as a dynamic bio-based crosslinker in a DLP-compatible resin, resulting in materials with vitrimeric behavior, self-healing capability, and effective recyclability. Overall, this thesis demonstrates the potential of waste-derived cellulose as a versatile and sustainable building block for advanced photocurable and 3D-printable functional materials, contributing to the development of circular and environmentally responsible additive manufacturing technologies.