Order Parameters ⟨P2⟩, ⟨P4⟩, and ⟨P6⟩ of Aligned Nematic Liquid-Crystalline Polymer As Determined by Numerical Simulation of Electron Paramagnetic Resonance Spectra

Abstract

High rank order parameters may comprise substantial information about molecular orientational distribution of liquid-crystalline materials. There are few experimental procedures targeted at the determination of high rank order parameters. We suggest a procedure for the determination of order parameters of a spin probe by numerical simulation of electron paramagnetic resonance (EPR) spectra. The procedure is based on revealing the molecular orientation axis of a spin probe. Order parameters <P(2)>, <P(4)>, and <P(6)> of the spin probe in aligned liquid-crystalline polymer have been measured by the suggested procedure. It was shown that the procedure gives more reliable and complete characteristics of molecular order than does polarized UV-visible spectroscopy.