Effect of Rigidity of a Polymer Matrix on the Photochemical Transformations of Photochromic Compounds

The thermal and thermomechanical properties of polyurethanes based on isophorone diisocyanate and polyfurit crosslinked using various curing agents are studied by differential scanning calorimetry and dynamic mechanical analysis. Two transitions are observed on thermograms in the temperature range from –100 to +150°С. The first transition detected at a temperature below –60°С corresponds to the glass transition temperature of soft ester segments. A broad endothermic region (near 100°С) is related to the melting of crystal-like ordered structures formed by strong hydrogen bonding between hard segments. The relationship between the spectral-kinetic behavior of the photochromic compound introduced into the polymer matrix and the properties of the polyurethanes is investigated. The rate of photochemical transformations of the photochromic compound covalently bonded to the matrix may depend on the stage of the polymerization process at which it is introduced into the polymer.