1D Hypo-Crystals : Crystallization of Stereo-Irregular Polymers with Entropy diluent
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초록
내용
In this study, we introduce highly-ordered and closely packed, extended amorphous polymers such as poly(methyl methacrylate) (PMMA) by thermal quenching of the molten solution of polymer/volatile cryatallizable additive (VCA). Resultant PMMA films showed 1D crystallinity due to ordered lateral packing between chains which is independent on the tacticity while the packing is amorphous-like for the other two directions. We named the crystalline PMMA as 1D hypo-crystalline PMMA (hc-PMMA). Surprisingly, small angle X-ray scattering (SAXS) revealed unprecedented extended conformation of PMMA in the molten PMMA/VCA solutions. Specific VCA such as BA which induces spontaneous chain-stretching in solution was designated entropy diluent. Upon quenching, PMMA chains are further stretched because of the large tensile stress induced by the sudden temperature drop and because of mechanical squeezing by concomitant directional crystallization of anisotropic lath-like BA crystals.