Sn-containing liquid crystalline side group homopolymers with two glass transitions

Three homologous tin-containing homopolymers with a terminal CN-dipole in the side group have been synthesized and characterized by dynamical calorimetry, polarization microscopy, X-ray and dielectric methods. AFM was used to evaluate the texture at room temperature. Four different phase transitions were detected by DSC. The high temperature phases were identified by polarization microscopy as SmA and SmC. AFM-measurements show focal-conic domains at room temperature and confirm so the smectic nature of all phases. X-ray measurements on nonoriented samples give hints to a phase segregation on nanometer scale. Dielectric investigation and temperature-modulated DSC (TMDSC) confirm clearly phase separation by appearance of two glass transitions related to the liquid order of the main chains and the liquid crystalline of the side groups.