This study focuses on the morphology and crystallization behavior of the blends of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer, poly(ethylene oxide) (PEO) and poly(L-lactide) (PLLA) homopolymers, which revealed an unusual crystallization behavior ascribed to the strong confinement effect associated with the quite narrow lamellar microdomains formed in the PS-b-PMMA/PEO/PLLA blends. Over the compositions studied, the blends were found to display microphase-separated structures, in which the PMMA block chains, PEO and PLLA homopolymers could form a mixture in their microdomains confined within the PS matrix. Interestingly, in the PEO-rich blends (with comparison to the amount of added PLLA) forming the lamellar morphology, the PEO component confined in the lamellar microdomains with the PMMA block and the PLLA homopolymer in the blends did not crystallize or only exhibited a limited degree of crystallinity. We propose that the possible mechanism for such unusual crystallization behavior of PEO was ascribed to the strong confinement effect imposed by a quite narrow domain size within the MMA/EO/LA lamellar microdomains formed in the PEO-rich blends. Nevertheless, the crystallinity of PEO in the oriented PEO-rich blends by large-amplitude oscillatory shear can be slightly increased, in which the c-axis along the chain direction of PEO crystals to the domain interface was tilted at an angle of ca. 49o.

Morphology and unusual crystallization behavior in diblock copolymer/homopolymer blends

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.