Thermal expansion of liquid crystalline amphiphilic di-block copolymer observed by simultaneous DSC-XRD

Phase transition process of PEOm-b-PMA(Az)(n) was investigated by the simultaneous DSC-XRD measurement using the synchrotron radiation facility. Four endothermic DSC peaks were observed during heating process. These DSC peaks were assigned to the melting of PEO, the transition from SmX, which is a mixture of super-cooled SmC and crystal, to SmC, from SmC to SmA, and from SmA to isotropic liquid state as determined by XRD profiles. In SmC phase, the liner expansion coefficient calculated from the spacing variation of the smectic layer distance was larger than that of the other phases. This result reflected the fact azobenzene moieties in the long-side chains of PMA(Az)(n) forming the smectic layers and then they were tilted and stood up during the heating process.