三嵌段共聚物在选择性溶剂中从层状到六方堆积圆柱体的相变动力学
Kinetics of phase transition from lamellar to hexagonally packed cylinders for a triblock copolymer in a selective solvent
摘要：
利用时间分辨小角X射线散射（SAXS）研究了聚苯乙烯-b-聚（乙烯-co-丁烯）-b-聚苯乙烯（SEBS）三嵌段共聚物在聚苯乙烯（PS）的选择性溶剂邻苯二甲酸二丁酯（DBP）中从层状相（LAM）向六方填充圆柱相（HEX）转变的动力学。由于DBP对PS嵌段的溶剂选择性，我们在比LAM相更低的温度下观察到在核中具有EB嵌段的HEX相。对远低于LAM-HEX转变温度的深温淬火的SAXS数据的分析表明，转变发生在一个单步过程中。我们计算的散射使用的几何模型的波纹层与相邻层完全不同相的转换过程中。计算与数据的一致性进一步支持了从LAM到HEX的深度淬火的连续转化机制。相比之下，对于接近OOT的浅淬火，我们发现与两步成核和生长机制的协议。
英文摘要：
We examined the kinetics of the transformation from the lamellar (LAM) to the hexagonally packed cylinder (HEX) phase for the triblock copolymer, polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) in dibutyl phthalate (DBP), a selective solvent for polystyrene (PS), using time-resolved small angle x-ray scattering (SAXS). We observe the HEX phase with the EB block in the cores at a lower temperature than the LAM phase due to the solvent selectivity of DBP for the PS block. Analysis of the SAXS data for a deep temperature quench well below the LAM-HEX transition shows that the transformation occurs in a one-step process. We calculate the scattering using a geometric model of rippled layers with adjacent layers totally out of phase during the transformation. The agreement of the calculations with the data further supports the continuous transformation mechanism from the LAM to HEX for a deep quench. In contrast, for a shallow quench close to the OOT we find agreement with a two-step nucleation and growth mechanism.
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