Phase transition behavior of silicone based liquid crystalline polymers

Abstract

Phase transition behavior of silicone based liquid crystalline (LC) polymers with variable isotropic transition temperatures (T i ), synthesized from poly(methyl hydrosiloxane), 10-undecenoic acid based crosslinking agent and cholesterol based side chain mesogen, was studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. The chemical structure of the mesogenic monomer and the LC polymers were confirmed by Fourier transform infra-red (FT-IR) spectroscopy and 1 HNMR spectroscopy. DSC studies showed that the glass transition temperatures (T g ) and T i of the LC polymers decreased with increasing proportion of mesogenic crosslinking agent at its low proportion and at its higher proportion T i disappeared completely indicating that the polymeric chains had less chance to orient in the network structure. The results were consistent with the XRD and POM studies.