SYNTHESIS AND PHYSICAL-PROPERTIES OF LIQUID-CRYSTALLINE ALKYL ISOCYANATE COPOLYMERS

A series of alkyl isocyanate homopolymers and copolymers were synthesized to investigate the influence of alkyl chain length on physical and chemical properties, especially decomposition behavior. In a series of undecyl isocyanate copolymers containing 50 mol % of ethyl, propyl, butyl, hexyl, and octyl isocyanate, a mild upward trend was found for the clearing temperature, whereas the crystal-to-nematic transition temperature remained unchanged at about 108 °C. Glass transitions were also found; they fell and then rose as the comonomer chain length increased. Thermal gravimetric analysis showed that copolymerization provided no improvement in stability; all polymers decomposed at around 180 °C. However, the isotropic temperature range is improved by copolymerization due to the depression of the clearing temperature. © 1990, American Chemical Society. All rights reserved.