Effect of the Core/Shell Particle Synthesis Method on the Physico–Chemical Properties of Their Shell and Sensory Properties of 3D-Ordered Films

In this work, we investigated the influence of the synthetic conditions of core/shell particles on physico–chemical properties of their shells, the process of self-assembly of particles into 3D-ordered structures, and the sensitivity of films based on these particles to the presence of ethanol and temperature changes. The core/shell particles were prepared by two methods: seed emulsion copolymerization and semi-batch emulsion copolymerization. The cores consisted of polystyrene or its copolymer with methyl methacrylate. Polymer shells of the particles were obtained by copolymerization of methyl methacrylate with several acrylate comonomers: butyl acrylate, butyl methacrylate, propyl acrylate, and ethyl acrylate. The photonic crystal films with the highest sensitivity to ethanol vapors were obtained on the basis of the core/shell particles synthesized by semi-batch emulsion polymerization. It was also established that introducing butyl acrylate or propyl acrylate units into shell copolymers led to an increase in the sensitivity of the resulting photonic crystal films. The films demonstrated a pronounced thermosensitivity only when the corresponding core/shell particles were synthesized as follows: the shell comonomers (methyl methacrylate and butyl acrylate) were introduced into the reaction system during the semi-batch emulsion process in a single step. The intensity of the photonic band gap (PBG) peak for these films decreased by 100% at around 42 °C.