Multimesophase transitions of main-chain liquid crystalline copolymers with strictly alternating fluorocarbon chains

Main-chain liquid crystalline polymers seldom develop into a columnar phase, let alone mesophase transitions between the columnar phase and other phases as the temperature changes. Herein, we present a new series of main-chain liquid crystalline copolymers which consist of strictly alternating rod-like aryl ester core, alkyl chain and perfluoroalkyl segments synthesized by photoinduced step transfer-addition and radical-termination (START) polymerization. The mesophases can be adjusted by changing the length of alkyl chains or perfluoroalkyl segments, which have been fully investigated and simulated in terms of molecular arrangements of molecules. Importantly the resultant liquid crystalline copolymers can present rare reversible phase transitions from a hexagonal columnar phase to a rectangular columnar phase and finally to a smectic phase with temperature increasing.