Morphology and Crystal Structure of PS-b-PEO/PS-b-PMMA Blends

Abstract

We investigated the phase and crystallization behaviors of binary block copolymer blends composed of poly(styrene-block-(ethylene oxide) (PS-b-PEO) and poly(styrene-block- methyl methacrylate) (PS-b-PMMA) The micro-domain morphology changed with relative chain lengths between PS-b-PEO and PS-b-PMMA In symmetric PS-b-PEO /symmetric PS-b-PMMA blends the blends formed a lamellar micro-domain morphology because the volume fraction of the PS micro-domain was approximately 0 5 By contrast in asymmetric PS-b-PEO/symmetric PS-b-PMMA blends macro-phase separation occurred when a high amount of PS-b-PMMA was added to the blends resulting in the coexisted lamellar micro-domain morphologies with different micro-domain size Such behavior was attributed to the poor compatibility between PEO and PMMA in high PMMA content Moreover the addition of PS-b-PMMA caused decreased in the melting point crystallization temperature crystallization and degree of crystallinity The effects depended on molecular weight difference between PEO and PMMA Furthermore we blended PS-b-PEO with different molecular structures of PMMA(PMMA homopolymer and PS-b-PMMA block copolymer) and compared them with the PEO/PMMA blend The crystallization temperature and crystallinity were in the order of PEO/PMMA> PS-b-PEO/PS-b-PMMA>PS-b-PEO/PMMA In addition crystal orientation varied with different molecular structures of PMMA because different dispersion states of PMMA in the PS-b-PEO micro-domain morphology PEO-crystal orientation was also changed with crystallization temperature

Date of Award	2020
Original language	English
Supervisor	Chieh-Tsung Lo (Supervisor)