Amphiphilic mesogen-jacketed liquid crystalline polymers: Design, synthesis, and self-assembly behaviors

We synthesized a series of amphiphilic mesogen-jacketed liquid crystalline (LC) polymers with a biphenyl side-chain mesogen containing a carboxylic acid group on one side and an octyloxy group on the other, and the number of methylene units between the biphenyl core and the exterior carboxylic acid group was varied to adjust the mesophases and the amphiphilic nature. The polymers were obtained through conventional radical polymerizations and characterized by a combination of different techniques such as thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy, and X-ray scattering. The results revealed that the polymer without any methylene spacer, POBP-0C, did not exhibit LC properties while POBP-1C (n = 1) and POBP-7C (n = 7) formed double layer smectic A (SA) phases. The hydrogen bonding among the carboxylic acid groups and the segregation between the carboxylic acid groups and the alky chains played important roles in forming the mesophases. In addition, the solution self-assembly behaviors were also preliminarily investigated through the fluorescent probe technique and transmission electron microscopy, and vesicles with uniform sizes were observed. The weak hydrophilicity and large degree of freedom of the carboxylic acid group and the relative rigidity of the polymer chain due to the jacketing effect were responsible for the formation of the structures. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012