Development of degradable thermosets and laminated films with cellulose nanofibers: From new bio-based monomer composed of geraniol and 2,5-furandicarboxylic acid

The development of biomass-based and recyclable thermosets has been an elusive technological priority in the development of sustainable plastics. Here, we introduce the synthesis of a new, fully bio-based alkene monomer (GFG). The monomer, derived from geraniol and 2,5-furandicarboxylic acid (FDCA) via esterification, was used to develop degradable thermosets through thiol-ene click reactions. The resulting thiol-ene network incorporating GFG demonstrates significantly improved mechanical and thermal properties compared to those of conventional geraniol-based thiol-ene networks. The Young's modulus of the networks ranged from 47 to 923 MPa, and the ultimate tensile strength was 22–25 MPa, thereby offering tunable mechanical properties that meet the requirements of specific applications. With a glass transition temperature of 30–40 °C, the networks also showed enhanced thermal stability owing to the integration of FDCA and increased crosslinking density. Evaluation of the environmental impact of these GFG-based thermoset networks by subjecting them to alkaline hydrolysis confirmed their degradability and chemical recyclability. Additionally, laminating these thermosets with cellulose nanofiber films resulted in flexible and sustainable composite films that are strongly adhesive and optically transparent. These results indicate that the GFG-based networks offer a promising and biodegradable alternative to flexible substrates, with potential application in flexible electronics, packaging, and other fields that require sustainability. • A new bio-based monomer was synthesized from geraniol and 2,5-furandicarboxylic acid. • Curing via the thiol-ene click reaction was used to prepare a degradable thermoset. • The thermosets have superior physical properties compared with conventional networks. • The composite with cellulose nanofibers yields flexible and transparent films. • These materials have potential for flexible, transparent, and degradable substrates.