Synthesis of liquid crystalline polyesters of various types by acyclic diene metathesis polymerization

Abstract

A series of liquid crystalline polyesters of different types were prepared by the acyclic diene metathesis polymerization method. These polymers are of main-chain, side-chain, and combined types. Polymerizations were conducted at 25-50 degrees C either in solution or in bulk using the so-called Grubbs' catalyst, bis(tricyclohexylphosphine)benzylideneruthenium dichloride. The monomers utilized in this investigation are all isolated dienes containing a built-in aromatic type mesogenic unit or an aromatic ester type mesogen bearing the cholesterol pendant through oxydodecyloxy spacer or monomesogenic terephthalate ester unit bearing the cholesterol pendant through a spacer. Bulk polymerization produced higher MW polymers than solution polymerization as expected from the known polymerization mechanism. Liquid crystallinity and phase transition properties of obtained polymers were studied by differential scanning calorimetry, optical microscopy, and X-ray diffraction.