Forming Asymmetric Phase Diagram Using A<SUB>1</SUB>(A<SUB>2</SUB>B)<SUB>5</SUB> Miktoarm Star Block Copolymers
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초록
내용
We synthesized polystyrene-block-(polystyrene-block-poly(2-vinylpyridine))5 [PS-b-(PS-b-P2VP)5] and investigate the morphologies changed by the volume fraction and chain asymmetry. According to the simulation data, we found that A1(A2B)5 can achieve the asymmetric phase diagram which is different from that of linear block copolymers. Especially, the phase diagram could be way more shifted when the chain asymmetry (τ = ƒA1/ƒtoalA) is about 0.75. In this study, we synthesized PS-b-(PS-b-P2VP)5 by anionic polymerization and ATRP, followed by analyzing the characteristics of polymers by GPC and NMR. When the ƒPS of PS-b-(PS-b-P2VP)5 was 0.82 and τ was 0.76, we could observe asymmetric lamellar structure, which was confirmed by TEM and SAXS. We also found the cylindrical and gyroidal structures at ƒPS = 0.6~0.7. Therefore, we concluded that the complex architecture of PS-b-(PS-b-P2VP)5 greatly affects the microdomain and leads to asymmetry of the phase diagram.