Copolymer Considerations on the Displacing Effect for the Effective Functionalization of 3D-Printed Photopolymer...

This study is part of a research effort motivated by the effective nanofiller functionalization of polymers for 3D printing sensors, enabling the fine-tuning of their functional properties. While the aspects of various conductive fillers, including their morphology, concentration, dispersion, and surface modification, are widely studied, the dispersing medium receives far less attention. Previously, we revealed a significant effect of conjugated electrons on the overall dielectric properties of filled aromatic polymers. This work examines another aspect of the complex interactions in multicomponent nanocomposite resins by investigating homopolymers and copolymers of two nonconjugated acrylic precursors with seemingly similar dielectric properties after curing but different orientational polarizability in the liquid state. Multiwalled carbon nanotubes (MWCNTs) are employed as a model filler. The results linked rheological, dielectric, and photopolymerization properties with performance in a simple capacitance-correlated strain-sensor setup. It revealed nontrivial and unintuitive effects, scaling the functional properties up to an order of magnitude. The best sensors achieved a sensitivity of 57 pF per 1% of strain, linearity of 0.99, and drift below 1.5% after 500 cycles. These were attributed to the adjusted filler dispersion through the displacement effect, which was fueled by the presence of the second monomer acting as a cosolvent. The results guide the path to improved sensor performance and effective nanofiller functionalization while providing critical material considerations for future academic research and industrial development.