Growth of Gyroid Grains in the Complex Phase Window of PS-b-PI/PS Blends

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• 作者：Vincent H. Mareau ; Tadashi Matsushita ; Eiji Nakamura ; Hirokazu Hasegawa
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：September 18, 2007
• 年：2007
• 卷：40
• 期：19
• 页码：6916 - 6921
• 全文大小：800K
• 年卷期：v.40,no.19(September 18, 2007)
• ISSN：1520-5835

文摘

The nonequilibrium microphase separation process taking place in polystyrene-block-polyisoprene(SI)/polystyrene (hS) blends during solvent evaporation was investigated by transmission electron microscopy tofind a way to grow large gyroid single grains free of defects to be used as photonic crystals. Complex microdomainmorphologies-gyroid, perforated layers (PL), and sponge-were found in a narrow region of the blend composition(complex phase window), and two different gyroid growth paths were identified for different blend compositions,both of them following a nucleation and growth process but resulting in different gyroid grain qualities. (1)64/36 wt % (SI/hS): gyroid grains grow from sponge phase and reject part of the hS finally trapped as defectswhen small grains coagulate to form larger imperfect gyroid grains. (2) 67/33 wt % (SI/hS): gyroid and PLgrains nucleate and grow consuming sponge, and then gyroid consumes faster growing PL. The lower nucleationdensity of gyroid grains results in defect-free large grains though surrounded by a small amount of accumulatedhS domains. The second growth path, still requiring improvements, offers a promising method to grow largegyroid single crystals.