Modeling physico-mechanical properties of an individual photopolymerization-induced urethane-based microgel particle

Abstract

In this work, an individual microgel particle dispersed in a viscous-like matrix was synthesized through the in-situ photopolymerization process. The actual size of the individual microgel particle was calculated based on the microscopic techniques. The cooperative relaxation properties of the individual microgel particle were studied using dynamic mechanical analysis technique. A value of 18 of dynamic fragility index for the microgel network was obtained. The size of cooperatively rearranging region (CRR) at the glass transition temperature for the microgel particle was estimated to be 6. A value of 0.041 mol/cm3 of cross-link density of the individual microgel particle was predicted based on the atomic force microscopy results and stress-strain data. The microgel hardness was measured by a nano-indentation instrument with an indenter diameter of 150 nm. The value of the hardness of the microgel particle was found to be in a suitable agreement with the results obtained from the atomic force microscopy technique. On the basis of a proposed model, the apparent diffusion coefficient of Cl− through the photopolymerization-induced microgel particle was calculated to be about 10 μm2/sec.