Kinetics and mechanisms for the cylinder-to-gyroid transition in a block copolymer solution

被引:110
作者
Wang, CY
Lodge, TP [1 ]
机构
[1] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA
[2] Univ Minnesota, Dept Chem Engn & Mat Sci, Minneapolis, MN 55455 USA
关键词
D O I
10.1021/ma0205212
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
The cylinder-to-gyroid transition in a block copolymer solution has been studied using a combination of rheology and small-angle X-ray scattering (SAXS). A poly(styrene-b-isoprene diblock copolymer with block molecular weights of 11000 and 32 000 g/mol, respectively, dissolved in the styrene-selective solvent di-n-butyl phthalate (DBP) at a volume fraction of 0.67 exhibits an order-order transition between hexagonally packed cylinders (C) and the cubic gyroid phase (G) at 74 +/- 3 degreesC. A shear-oriented C phase transforms to G epitaxially, as previously established in melts. For shallow quenches into G, the, transition proceeds directly by a nucleation and growth process. For deeper quenches, a metastable intermediate structure appears, with scattering and rheological features consistent with the hexagonally perforated layer (HPL) state. The appearance of the HPL state beyond a certain quench depth is reconciled with previous experiments and theory for the lamellar (L)-to-gyroid transition. The C --> G transition follows the same pathways, and at approximately the same rates, even when the initial C phase is not shear-oriented. The transition rates are quantified as a function of quench depth. The reverse G --> C transition demonstrates a memory of the initial cylinder orientation that persists even after annealing the G phase for 48 h. The results are discussed and compared with related work in the literature.
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收藏
页码:6997 / 7006
页数:10
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