A new periodic pattern with five-neighbored domain packing from ABC triblock terpolymer/B homopolymer blend

作者：Izumi Yuki; Yamada Mutsuhiko; Takano Atsushi; Matsushita Yushu^*

来源：Journal of Polymer Science Part B: Polymer Physics , 2015, 53(13): 907-911.

DOI：10.1002/polb.23714

• ABC triblock terpolymer
• blend
• homopolymer
• periodic pattern
• self-assembled structure

Self-assembled structures from poly(isoprene-b-styrene-b-2-vinylpyridine)(ISP)/styrene homopolymer blend were investigated. Five terpolymers whose total molecular weight, M, is in the narrow range of 121k<M<214k, and volume fractions of the center block polystyrenes, phi(S), are similar at around 0.55, were prepared as parent block terpolymers. Their phi(P)/phi(I) ratios, used as an indicator of asymmetry, are varied in the range 0.32<phi(P)/phi(I)<2.46. Three low-molecular weight styrene homopolymers with molecular weights of 3k, 9k, and 12k, respectively, were mixed with those block terpolymers to produce blends with almost constant styrene content within the range 0.65<phi(S)<0.68. Both ISP/S(3k) and ISP/S(12k) blend series show a morphological transition from tetragonally packed cylinders (TPC) to double hexagonal structure (DHS) with hexagonally arrayed polyisoprene cylinders, each surrounded by six thin cylinders as satellites. If one focuses on ISP-III(150k)/S blends whose phi(P)/phi(I) is 0.88, TPC for ISP-III/S(3k) was transformed to DHS for ISP-III/S(12k), evidently due to the molecular weight effect of the added homopolymer. Finally a new periodic pattern, having P cylinders surrounded by five I cylinders each, has been discovered from ISP-III/S(9k) at overall composition of phi(I)/phi(S)/phi(P)=0.17/0.68/0.15 and polystyrene block/styrene homopolymer ratio of w(S)(b)/w(S)(h)=1.4. This structure was confirmed to possess hexagonal symmetry with larger unit cell than regular patterns ever known by X-ray diffraction experiment.

• 出版日期2015-7-1