Reid Barry, Alvarez-Fernandez Alberto, Schmidt-Hansberg Benjamin, Guldin Stefan
Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , U.K.
BASF SE, Process Research & Chemical Engineering, Coating & Film Processing , Carl-Bosch-Strasse 38 , 67056 Ludwigshafen am Rhein , Germany.
Langmuir. 2019 Oct 29;35(43):14074-14082. doi: 10.1021/acs.langmuir.9b03059. Epub 2019 Oct 16.
The functionality and applications of mesoporous inorganic films are closely linked to their mesopore dimensions. For material architectures derived from a block copolymer (BCP) micelle coassembly, the pore size is typically manipulated by changing the molecular weight corresponding to the pore-forming block. However, bespoke BCP synthesis is often a costly and time-consuming process. An alternative method for pore size tuning involves the use of swelling agents, such as homopolymers (HPs), which selectively interact with the core-forming block to increase the micelle size in solution. In this work, poly(isobutylene)poly(ethylene oxide) micelles were swollen with poly(isobutylene) HP in solution and coassembled with aluminosilicate sol with the aim of increasing the resulting pore dimensions. An analytical approach implementing spectroscopic ellipsometry (SE) and ellipsometric porosimetry (EP) alongside atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) in transmission and grazing-incidence (GISAXS) modes enabled us to study the material evolution from solution processing through the manifestation of the mesoporous inorganic film after BCP removal. The in-depth SE/EP analysis evidenced an increase of more than 45% in mesopore diameter with HP swelling and a consistent scaling of the overall void volume and number of pores. Importantly, our analytical toolbox enabled us to study the effect of swelling on the connecting necks between adjacent pores, with observed increases as high as ≈35%, offering novel pathways to sensing, electrochemical, and other mass-transfer-dependent applications.
介孔无机薄膜的功能和应用与其介孔尺寸密切相关。对于由嵌段共聚物（BCP）胶束共组装衍生的材料结构，孔径通常通过改变与成孔嵌段相对应的分子量来控制。然而，定制BCP合成通常是一个成本高昂且耗时的过程。另一种调节孔径的方法是使用溶胀剂，如均聚物（HP），它与形成核的嵌段选择性相互作用，以增加溶液中胶束的尺寸。在这项工作中，聚（异丁烯）聚（环氧乙烷）胶束在溶液中用聚（异丁烯）HP溶胀，并与硅铝酸盐溶胶共组装，目的是增加所得的孔径。一种分析方法，结合光谱椭偏仪（SE）和椭偏孔隙率测定法（EP）以及原子力显微镜（AFM）和小角X射线散射（SAXS）的透射和掠入射（GISAXS）模式，使我们能够研究从溶液加工到去除BCP后介孔无机薄膜形成过程中的材料演变。深入的SE/EP分析表明，HP溶胀后介孔直径增加了45%以上，总体孔隙体积和孔隙数量也相应增加。重要的是，我们的分析工具箱使我们能够研究溶胀对相邻孔隙之间连接颈的影响，观察到的增加高达约35%，为传感、电化学和其他依赖传质的应用提供了新途径。
