In-situ polymerization of epoxy based thermotropic liquid crystalline polymers by reactive extrusion and its liquid crystalline behaviors.
Seo Yongsok (1)*
(1) Seoul National University, Dept. Materials Sci. Eng. - Seoul - Korea
A new series of thermotropic liquid crystalline polymer (TLCP) containing three phenyl ring connected by an ester mesogenic unit are synthesized by reactive extrusion method. In twin screw extruder, main chain TLCP had been in-situ polymerized from the liquid crystalline epoxy (LCE) monomer reacted with monoamine in several minutes. The chemical structure of TLCP was characterized by means of Fourier-transform infrared (FT-IR) spectrometer, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The thermal properties and thermotropic liquid crystalline behaviors were investigated by Thermal gravimetric Analysis (TGA), Differential scanning calorimetry (DSC), 2-D high temperature X-RAY Diffraction (2-D XRD) with GADDS (General Area Detector Diffraction System) program and Polarized light Optical Microscopy (POM) with hotstage. All the series of TLCPs revealed nematic LC transition behavior and exhibited Shlieren or marbled texture depended on their chemical structures. The nematic-to-isotropic transition temperatures were existed in the range of 175 to 240, and TLCPs were thermally stable up to 350. The molecular weight of TLCPs were determined by Gel permeation chromatography (GPC) and the values of Mn were in the range of 8,600 to 24,100.