Influence of the Surface Field on the Self-Assembly of a Diblock Copolymer Melt Confined in a Cylindrical Nanopore
Influence of the Surface Field on the Self-Assembly of a Diblock Copolymer Melt Confined in a Cylindrical Nanopore
复制标题
表面场对限制在圆柱形纳米孔中的二嵌段共聚物熔体自组装的影响
DOI：
10.1021/ma900667w
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发表时间：
2009-10-13
期刊：
影响因子：
5.5
通讯作者：
Wickham, Robert A.
中科院分区：
文献类型：
--
作者：
Li, Weihua;Wickham, Robert A.
我们利用自一致平均场理论研究了表面场对限制在圆柱形纳米孔中的二嵌段共聚物熔体中形成的片层形貌的影响。通过改变孔径和表面场强度，并引入轻微的成分不对称，系统地探索了平行和垂直层状相的稳定区域，并精确地计算了相边界。当表面场较弱，或片层的自然周期与孔径不适应时，片层优先选择垂直于孔壁的片层。强烈的表面偏好和/或较小的成分不对称性可导致同心平行片层的形成。在狭窄的孔隙中，我们发现复杂的结构可以作为平行和垂直片层区域之间的平衡相存在。当我们减少孔壁偏好的块体体积分数时，这种成分的不对称性与表面偏好竞争，并导致垂直片层的形成。这提示了在存在表面偏好的普通实验情况下产生垂直层状相的途径。这种竞争也使我们能够在理论中表征表面场的强度。
We study the influence of the surface field on lamellar morphologies that form in a diblock copolymer melt confined in a cylindrical nanopore, using self-consistent mean-field theory. By varying the pore diameter and surface field strength and by introducing a slight composition asymmetry, we systematically explore the stability regions of parallel and perpendicular lamellar phases and accurately compute the phase boundaries. When the surface field is weak, or the natural period of the lamellae is incommensurate with the pore size, lamellae perpendicular to the pore wall are preferred. A strong surface preference and/or a small composition asymmetry can lead to the formation of concentric parallel lamellae. In narrow pores, we find that complex structures can exist as equilibrium phases between regions of parallel and perpendicular lamellae. When we reduce the volume fraction of the block preferred by the pore wall, this composition asymmetry competes with the Surface preference and call lead to the formation of perpendicular lamellae. This suggests a route to produce perpendicular lamellar phases in the common experimental situation where a surface preference is present. This competition also enables us to characterize the strength of the surface field in the theory.