Hyperbranched photo responsive and liquid crystalline azo‐siloxane polymers synthesized by click chemistry

Abstract

Abstract Three new types of hyperbranched photoactive liquid crystalline siloxane polymers containing azo moieties were synthesized using click chemistry methodology. The polymers were soluble in most of the polar solvents like chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulphoxide and dichloromethane. The molecular weights of the polymers were in the range of 9000–12,000 g mol −1 . The trans‐cis photoisomerization of the polymer were studied both under UV radiation and dark. The isomerization rate constants were found to be in the range of 0.7–1.4 × 10 −2 sec −1 and 7.0 × −2.5 × 10 −5 sec −1 . The thermotropic behavior of the polymers was studied by using polarizing optical microscopy and differential scanning calorimetry, respectively. The polymers P1 and P2 showed liquid crystalline texture characteristic of nematic phase. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012