Side chain liquid crystalline polysiloxane hydroxamic acids and their liquid crystalline behaviour

Abstract

The synthesis and properties of side chain polysiloxane hydroxamic acids have been described. The N-p substituted phenyl hydroxamic acids were synthesized by reacting p - allyloxy benzoyl chloride and acryloyloxy sebacoyl chloride with N-arylhydroxylamines in toluene medium, rendered basic with aqueous suspension of sodium bicarbonate at 0 °C or lower. The synthesized N-phenyl substituted hydroxamic acids were attached to poly(methylhydrosiloxane) via hydrosilylation reaction in the presence of platinum catalyst The polysiloxane hydroxamic acids were characterized by melting point, FT – IR, NMR and Mass spectral techniques. The liquid crystalline behaviour of the side chain polysiloxane hydroxamic acids with allyloxy and acryloylsebacoyloxy spacer have been studied by optical.polansed microscopy and differential scanning calorimetry. Side chain liquid crystalline polysiloxane hydroxamic acids with allyloxy spacer (N-p substituted phenyl p-[(3-polysiloxane propyloxy) benzo] hydroxamic acids, (PHA – 1 to PHA −4) show nematic phases, while the second series with acryloylsebacoyloxy spacer (N-p-substituted phenyl (3-polysiloxane propanone) octyl carbonyloxy hydroxamic acids, (PHA – 5 to PHA – 8) show nematic as well as smectic phases. The liquid crystalline behaviour of the side chain polysiloxane hydroxamic acids with allyloxy and acrylsebacoyloxy spacer have been studied.