| Abstract: | Crystal and phase morphologies and structures determined by self-organization of crystalline-amorphous diblockcopolymers, crystallization of the crystallizable blocks, and vitrification of the amorphous blocks are reviewed through asystematic study on a series of poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymers. On the base ofcompetitions among these three processes, molecular and supramolecular ordering in confined environments can beinvestigated. In a concentration-fluctuation-induced disordered (DCF) diblock copolymer,the competition between crystallization of the PEO blocks and vitrification of the PS blocks is momtored by time-resolved simultaneous small angle X-ray scattering (SAXS) and wide angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD) techniques.In the case of Tc<TgPS-rich,the crystallization of the PEO blocks is observed to be confined within the bicontinuous DCF phase due to the rapid vitrification of the PS-rich phase.Overall crystallization rate,crystal melting behavior,and crystallinity results further confirm the competition between crystallization and vitrification at different temperatures.In an ordered lamellar PEO-bPS diblock copolymer,the crystallization of the PEO blocks is completely confined within the ordered lamellae due to rapid vitrification of the PS layers as observed by time-resolved SAXS and WAXD experiments.From the combined two-dimensional SAXS and WAXD measurements,the crystal orientation within the confined lamellar geometry is found parallel to the lamellar surface normal when it is isothermally crystallized at 35℃.In an ordered cylindrical PEO-b-PS sample,the crystallization of the PEO blocks is also observed to be confined within the ordered cylinders because of rapid vitrification of the PS matrix.The crystal orientation within the confined cylinders is found perpendicular to the cylinder axis as it is crystallized at 35℃. |
