A Liquid Crystal Based Polymer for Applications in MMW Modulation Devices

Abstract

A new liquid crystal monomer, the diacrylate of a bis phenyi diazene, was synthesized. It was polymerized to form both unoriented and oriented polymer solids–the latter in the presence of a magnetic field. The millimeter wave birefringence was measured for a polymeric rod, whose macroscopic orientation was perpendicular to its long axis, using a waveguide version of the Mach-Zehnder interferometer, and the measured δn was 0.075 at 30 GHz. The mechanical strength of oriented and unoriented polymer plates was measured. The tensile modulus in the direction parallel to the oriented axis was 6.8×108 N/m2, which was about 4 times that of the same material without macroscopic orientation. The torsional rigidity modulus of a thin rod (orientation perpendicular to its length) was measured to be of the order 107 N/m4. Both the large dielectric anisotropy and high mechanical strength make the oriented polymer potentially suitable for application in a novel class of millimeter wave modulation devices.