Photocurable Carbonaceous Composites with Tunable Piezoresistive Response

Abstract

Photocurable polymer composites with tailored electrical and mechanical properties is of growing interest for advanced manufacturing and (multi)functional applications. This study investigates how two carbonaceous fillers, carbon nanotubes (CNT) and reduced graphene oxide (rGO), affect the photopolymerization, nanoscale structure, and macroscopic properties of two photocurable resins with distinct mechanical nature: an elastic polyurethane acrylate (SPOT-E) and a rigid biobased acrylated epoxidized soybean oil (AESO). Photorheology reveals that CNT strongly inhibit curing above 0.6 wt.% due to optical shielding, while rGO enables complete curing up to 5 wt.%. Dispersion analysis indicates homogeneous distributions for both fillers, whereas mechanical analysis exhibits network deterioration at high filler contents. Quasielastic neutron scattering shows that fillers incorporation significantly restricted SPOT-E dynamics but enhanced AESO mobility, the effect depending on filler type and loading filler contents. These multiscale effects translate into electrical conductivities of 0.014 S/m (SPOT-E/CNT) and 7.5·10–5 S/m (AESO/rGO). Finally, piezoresistive assessment revealed maximum gauge factors of ~ 0.9 for SPOT-E/CNT and ~ 50 for AESO/rGO systems and stability over 700 cycles. These results provide essential insights into the interplay between filler morphology, photopolymerization, and multifunctional performance in UV-curable composites, enabling the rational design of materials with predefined properties for additive manufacturing and electronics applications.