Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films
Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films
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DOI：
10.1039/d0nr05132b
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发表时间：
2020-09-21
期刊：
影响因子：
6.7
通讯作者：
Guldin, Stefan
中科院分区：
文献类型：
--
作者：
Alvarez-Fernandez, Alberto;Reid, Barry;Guldin, Stefan
介孔无机薄膜是一种具有广泛应用前景的材料结构，包括传感、催化、保护涂层、能量产生和储存。在许多情况下，在10 nm长度尺度上对双连续多孔网络的精确控制对于它们的操作至关重要。一种特别有前途的结构形成途径是利用嵌段共聚物（BCP）胶束在溶液中作为牺牲结构导向剂的无机前体的共组装。该方法提供了孔径控制和孔形成块的分子量，并且与广泛的材料库兼容。另一方面，分子量依赖性阻碍了连续的孔调节，并且固有的聚合物分散性对孔径均匀性提出了挑战。为此，我们演示了如何色谱分离的BCP提供了一个强大的方法来控制所得的介孔薄膜的孔径和分散性。我们应用半制备型尺寸排阻色谱分离的多分散聚（异丁烯）-嵌段-聚（环氧乙烷）（PIB-b-PEO）BCP从放大合成。具有不同分子量和窄分散度的BCP级分的分离允许我们不仅用相同的BCP源材料将特征孔径从9.1 +/-1.5调整到14.1 +/-2.1nm，而且与未分级的BCP相比还显著降低了孔径分散度。我们的研究结果提供了一种从多分散原料中获得单分散BCP库的途径，并提供了关于大分子特性与所得结构导向介孔之间的直接关系的重要见解，特别是与分散性相关的。
Mesoporous inorganic thin films are promising materials architectures for a variety of applications, including sensing, catalysis, protective coatings, energy generation and storage. In many cases, precise control over a bicontinuous porous network on the 10 nm length scale is crucial for their operation. A particularly promising route for structure formation utilizes block copolymer (BCP) micelles in solution as sacrificial structure-directing agents for the co-assembly of inorganic precursors. This method offers pore size controlviathe molecular weight of the pore forming block and is compatible with a broad materials library. On the other hand, the molecular weight dependence impedes continuous pore tuning and the intrinsic polymer dispersity presents challenges to the pore size homogeneity. To this end, we demonstrate how chromatographic fractionation of BCPs provides a powerful method to control the pore size and dispersity of the resulting mesoporous thin films. We apply a semi-preparative size exclusion chromatographic fractionation to a polydisperse poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) BCP obtained from scaled-up synthesis. The isolation of BCP fractions with distinct molecular weight and narrowed dispersity allowed us to not only tune the characteristic pore size from 9.1 +/- 1.5 to 14.1 +/- 2.1 nm with the identical BCP source material, but also significantly reduce the pore size dispersity compared to the non-fractionated BCP. Our findings offer a route to obtain a library of monodisperse BCPs from a polydisperse feedstock and provide important insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity.