Morphology Transitions of Linear A1B1A2B2 Tetrablock Copolymers at Symmetric Overall Volume Fraction
Morphology Transitions of Linear A1B1A2B2 Tetrablock Copolymers at Symmetric Overall Volume Fraction
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线性 A1B1A2B2 四嵌段共聚物在对称总体积分数下的形态转变
DOI：
10.1021/acs.macromol.8b00567
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发表时间：
2018-06-12
期刊：
影响因子：
5.5
通讯作者：
Li, Weihua
中科院分区：
文献类型：
--
作者：
Ahn, Seonghyeon;Kim, Jin Kon;Li, Weihua
在保持PS嵌段和PI嵌段的对称体积分数(fPS1+fPS2：fPI1+fPI2≈1：1)不变的情况下，研究了线型四嵌段共聚物(S1I1S2I2)的形态转变。随着fPI1的增加，观察到了一系列有趣的形态转变：片层(L)、→不对称片层(AL)、→六方堆积PI柱体(CPI)、带有PI网络结构域的→双回旋体(GPI)、→短周期片层(SL)。SL的微区间距接近L的一半，而Al的PS和PI微区具有不对称的片层宽度。特别有趣的是，在具有对称总体积分数的线型嵌段共聚物中，观察到了圆柱状和回旋体的形态。实验观察到的形貌与自洽场理论(SCFT)预测的平衡相一致。
We investigated morphology transitions of linear tetrablock copolymers of polystyrene-block-polyisoprene-block-polystyrene-block-polyisoprene (S1I1S2I2) by varying volume fraction of PI1 block (fPI1), while maintaining the symmetric volume fraction of total PS blocks and PI blocks (fPS1+fPS2:fPI1+fPI2 ≈ 1:1). An interesting sequence of morphology transitions was observed as fPI1 was increased: lamellae (L) → asymmetric lamellae (aL) → hexagonally packed PI-cylinders (CPI) → double gyroid with PI-network domains (GPI) → short-period lamellae (sL). The domain spacing of sL was nearly half that of L, while aL had asymmetric lamellar width of PS and PI microdomains. It is particularly interesting that cylindrical and gyroid morphologies were observed in linear block copolymers with symmetric overall volume fraction at intermediate segregation. The experimentally observed morphologies are in good agreement with the predicted equilibrium phases by self-consistent field theory (SCFT).