AB Block-copolymers poly(oxyethylene)-blockpoly( dicyclohexyl itaconate): temperature dependence of the morphology

Abstract

The paper deals with AB block-copolymers poly(oxyethylene)-blockpoly(dicyclohexyl itaconate) (POE/PDCHI) containing 2000 and 5000 g/mol of the flexible POE. The study aims at revealing the thermal effect on the copolymer morphology in the 20 -200°C range. Optical microscopy investigations were performed. The results confirm our previous X-ray studies. A liquid crystalline state is observed in the 90 -180°C range. It is characterized by birefringence and is determined by the chair-chair conformation, a dominating structure of the cyclohexyl rings. A condis-crystal state is observed at cooling in the interval 90°C to room temperature. It is characterised by a variety of cyclohexyl conformations and, therefore, by a lack of birefringence. The PEO component in the copolymer starts crystallising into small local spherulites at about room temperature. The results obtained allow the conclusion that the presence of PDCHI is a determining factor for the mesomorphic state of the copolymers discussed.