Resin Chemistry-Driven Starch Reinforcement in Water-Free Photocurable Networks

Starch was added to water-free photocurable systems comprising biocompatible polymers (e.g., polyols and carbonates) in combination with methacrylic acid-based polymers to provide reinforcement despite its compatibility and processing challenges. Mechanical, thermal, FTIR, SEM, DMA, PSI, and gel fraction analyses were performed as functions of different combinations. The all-methacrylate formulation produced the highest tensile strength (17.0 MPa with 40% starch loading, along with a flexural strength of 13.8 MPa), while the highest flexural strength (17.1 MPa) was reported at lower starch loading with reduced tensile performance, indicating stiffening at the expense of toughness. Conversely, combinations involving biocompatible polymers, as well as the use of coupling agents, resulted in lower mechanical performance, as DMA and gel fraction results indicate more rigid network behavior in methacrylate-based systems, whereas more starch-compatible systems showed increased network heterogeneity and reduced uniformity, which demonstrated the influence of resin chemistry on starch incorporation in such systems.