Influence of Cross-Link Density on the Photopolymerization of Degradable Methacrylated Sugar Networks via Thiol-ene Chemistry

A series of biobased poly(ester-thioether) thermosets was developed from sugar-derived methacrylate monomers and characterized for their structure–property relationships. Xylose, glucose, and sucrose were functionalized via a one-step esterification with methacrylic anhydride to yield tetra-, penta-, and octa-methacrylated monomers, respectively. Thiol-ene photopolymerization with five dithiol cross-linkers produced 15 distinct thermoset networks. Fourier transform infrared spectroscopy (FTIR) confirmed successful cross-linking through the disappearance of the thiol peak at ∼2560 cm –1 . Thermal analysis revealed that temperatures at 5% weight loss ( T 5% ) and midpoint degradation temperatures ( T mid ) increased with cross-link density (ν c ), with sucrose-based networks exhibiting the highest thermal stability. Dynamic mechanical analysis (DMA) showed glass transition temperatures ( T g ) between 73 and 96 °C and an inverse relationship between molecular weight between cross-links ( M c ) and the storage modulus ( E ′), indicating that network rigidity is governed by both ν c and monomer architecture. Alkaline degradation studies confirmed ester hydrolysis by mass loss over time, with degradation rates influenced by network structure. Soil degradation exhibited minimal yet detectable environmental degradation, suggesting a balance between durability and eco-responsiveness. These results highlight the potential of sugar-derived multifunctional monomers for designing degradable, high-performance thermosets for stereolithography (SLA) and digital-light processing (DLP) 3D-printing resins, transparent coatings, and recyclable adhesive systems.