Molecular Orientation of Polyurethane Based Liquid Crystal Polymers by Corona Poling

Abstract

Molecular orientation induced by Corona poling of polyurethane based liquid crystalline polymers (LCPs) was studied using Fourier transform Infra-red with Grazing Incident Reflection Absorption Spectra (FTIR-GIRAS), Small-angle X-ray scattering (SAXS) and Atomic Force Microscopy (AFM). The FTIR-GIRAS spectra showed a reduction in peak intensity near 1729 cm^{− 1} due to bending of carbonyl group of urethane linkage. The P-E hysteresis curves showed higher remnant polarization (Pr) after poling. AFM showed numerous hills and valleys in the poled samples suggesting their use as piezoelectric materials. SAXS showed that the crystallinity of mesogenic monomer (cholesterol based) was reduced drastically in the polymers, however, the polymers with low a proportion (< 16.7 mol%) of cholesterol possessed a residual crystallinity. LCPs are proposed to be suitable for piezoelectric applications (actuator, sensor etc).

Keywords:

• Molecular orientation
• liquid crystalline polymer
• corona poling
• atomic force microscopy
• Small-angle X-ray scattering
• Piezoelectric materials

Acknowledgments

This research was supported by the 2008 KU Brain Pool Program of Konkuk University, South Korea, and Seoul R & BD Program (10848).

Notes

∗mol of MDI added in the 2nd stage reaction.