Surface Segregation and Self-Assembly of Block-Copolymer Separation Layers on Top of Homopolymer Substructures in Asymmetric Ultrafiltration Membranes from a Single Casting Step,Advanced Functional Materials

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Surface Segregation and Self-Assembly of Block-Copolymer Separation Layers on Top of Homopolymer Substructures in Asymmetric Ultrafiltration Membranes from a Single Casting Step
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-05-07 , DOI: 10.1002/adfm.202009387
Yusuke Hibi ₁ , Ulrich Wiesner ₁

Affiliation

Surface segregation in blended polymer films has attracted much interest in fundamental research as well as for practical applications. A variety of methodologies have been proposed for controlling surface segregation. They often require long annealing times, however, to achieve thermodynamic equilibrium. Here, a strategy and proof-of-principle experiments are described to control surface segregation of thin block-copolymer (BCP) layers on top of a homopolymer in a single casting step from blended BCP/homopolymer solutions. The surface coverage by the minor constituent BCP (2–10 wt%) is accomplished despite almost identical surface energies of BCP and homopolymer constituents. Immersing this casted solution into water for nonsolvent induced phase separation (NIPS), a nonequilibrium process, affords solidified bilayer ultrafiltration membranes composed of a thin porous surface layer of self-assembled BCP atop an asymmetric porous homopolymer substructure. Key to successful BCP surface segregation is the choice of a binary solvent system based on careful considerations of solvent surface energies and polymer-solvent interaction parameters. Furthermore, stabilizing the BCP micellar structure by a divalent metal additive is also essential. The approach provides a cost-effective method for fabricating bilayer-type asymmetric ultrafiltration membranes with uniform BCP self-assembly based selective top surface pore layers in a single casting step.

中文翻译：

单一浇注步骤的非对称超滤膜中均聚物亚结构顶部的嵌段共聚物分离层的表面分离和自组装

共混聚合物薄膜中的表面偏析引起了基础研究和实际应用的广泛兴趣。已经提出了多种方法来控制表面偏析。然而，它们通常需要较长的退火时间才能达到热力学平衡。在这里，描述了一种策略和原理验证实验，用于在单个浇铸步骤中控制均聚物顶部的薄嵌段共聚物 (BCP) 层从混合 BCP/均聚物溶液中的表面分离。尽管 BCP 和均聚物成分的表面能几乎相同，但次要成分 BCP (2-10 wt%) 的表面覆盖率仍可实现。将这种浇铸溶液浸入水中进行非溶剂诱导相分离 (NIPS)，这是一种非平衡过程，提供固化的双层超滤膜，该膜由位于不对称多孔均聚物亚结构顶部的自组装 BCP 的薄多孔表面层组成。BCP 表面分离成功的关键是在仔细考虑溶剂表面能和聚合物-溶剂相互作用参数的基础上选择二元溶剂系统。此外，通过二价金属添加剂稳定 BCP 胶束结构也是必不可少的。该方法提供了一种具有成本效益的方法，用于在单个浇铸步骤中制造具有均匀 BCP 自组装的选择性顶面孔层的双层型非对称超滤膜。BCP 表面分离成功的关键是在仔细考虑溶剂表面能和聚合物-溶剂相互作用参数的基础上选择二元溶剂系统。此外，通过二价金属添加剂稳定 BCP 胶束结构也是必不可少的。该方法提供了一种具有成本效益的方法，用于在单个浇铸步骤中制造具有均匀 BCP 自组装的选择性顶面孔层的双层型非对称超滤膜。BCP 表面分离成功的关键是在仔细考虑溶剂表面能和聚合物-溶剂相互作用参数的基础上选择二元溶剂系统。此外，通过二价金属添加剂稳定 BCP 胶束结构也是必不可少的。该方法提供了一种具有成本效益的方法，用于在单个浇铸步骤中制造具有均匀 BCP 自组装的选择性顶面孔层的双层型非对称超滤膜。

更新日期：2021-07-16

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