Solid-State 13C NMR Analyses of the Structure and Chain Conformation of Thermotropic Liquid Crystalline Polyurethane Crystallized from the Melt through the Liquid Crystalline State

Abstract

Solid-state 13C NMR analyses of the structure and chain conformation have been performed for a thermotropic liquid crystalline polyurethane that was polymerized from 3,3‘-dimethyl-4,4‘-biphenyldiyl diisocyanate, 1,10-decanediol, and 1-hexanol with a mole ratio of 25/24/2. This sample was crystallized by cooling from the isotropic melt through the liquid crystalline state at a rate of 1 °C/min. DSC thermograms of the cooling scan exhibit only one endothermic peak, whereas two exothermic peaks corresponding to the melting and isotropic points appear in the heating scan. However, the polarizing optical microscopic observation confirms that the crystallization occurs almost at the same time after the appearance of the liquid crystalline phase, although some part of the liquid crystalline phase is frozen without crystallization. T1C analyses reveal that the sample contains three components with different T1C values, which correspond to the crystalline, medium, and noncrystalline regions. From the line shape an...