Influence of cooling rate on the phase transitions of ferroelectric liquid crystals, MBOPDOB and MBOPDoOB

Abstract

The phase transitions of ferroelectric liquid crystals (FLCs), D-4-(2-methylbutyloxy)phenyl 4-decyloxybenzoate (MBOPDOB) and D-4-(2-methylbutyloxy)phenyl 4-dodecyloxybenzoate (MBOPDoOB), were investigated by means of differential scanning calorimetry (DSC) and polarizing microscopy. The DSC and polarizing microscopy results show that MBOPDOB and MBOPDoOB exhibit different phase transition sequences on slow cooling, whereas they have the same sequence under rapid cooling. In MBOPDoOB, we also observed a quench-induced metastable phase that differs from the normal crystal phase formed by slow cooling The textures corresponding to the two crystal phases were observed using a polarizing microscope. X-ray diffraction (XRD) was also used to study the quench-induced phase. The influence of the alkoxy chain length on the molecular interactions in FLCs is discussed. © 1999 Taylor & Francis Ltd.