Main-chain hybrid azobenzene-1,2,3-triazoleoligo(dimethylsiloxane) liquid-crystalline photoactive copolymers

The development of well-designed anisotropically ordered photoactive liquid-crystalline polymers has potential in the development of a number of areas related to high-tech light-responsive materials and devices, including photonics, optical switching, image storage, soft actuators, etc.The synthesis and characterization of a new type of photoactive linear main chain liquid-crystalline hybrid copolymers with regularly alternating molecular architectures is achieved for the first time through the use of azide-alkyne cycloaddition chemical reactions between a series of alkyne-terminated azobenzene molecules and azide-functional oligo(dimethylsiloxane) telechelics.The present investigation encompasses an array of chemical structures and molecular morphologies, thermodynamic properties, thermotropic liquid-crystalline and photoisomerization behaviors, and the influence of the azo-copolymer molecular composition on the polymers' microstructure, morphologies, and propensity towards thermotropic self-assembly into lamellar spherulitic structures.The kinetics of non-degradative reversible E-Z photoisomerization transitions and the relationship between the molecular composition of the polymers and their photoinduced isomerization behavior were investigated.The morphology and degree of anisotropy of physically cross-linked LCPs fibers prepared by the simple melt spinning method were studied.The results obtained provide important insights into the structure-property relationship of photoactive main chain hybrid azobenzene-siloxane LCPs, which are useful for the design of novel advanced photoactive polymers.