Through-Thickness Modulus Gradient and Pattern Fidelity of UV-Cured Thiol-Acrylate Films

The utilization of photopolymers in diverse applications such as microfluidic devices, gas inhibitors, and biomimetic tissues has surged due to advancements in digital light processing technologies that now support multimaterial platforms, facilitating micrometer-scale control over material heterogeneity. However, significant knowledge gaps remain in our understanding of spatiotemporal evolution within these multimaterial actinic films and layers. To help bridge these gaps, a thiol-acrylate system is employed for photopatterning, and atomic force microscopy is leveraged to map through-thickness modulus profiles at various UV exposure levels, in both flood and masked curing setups. This approach enables the evolution of material properties to be tracked through the film thickness for incremental light exposure durations and across different photopatterned feature sizes. The results illustrate complicated modulus profiles that highlight the complex interplay among light exposure parameters, polymerization kinetics, oxygen inhibition, and light scattering.