Vapaavuori Jaana, Grosrenaud Josué, Pellerin Christian, Bazuin C Geraldine
Département de chimie, Centre de recherche sur les matériaux auto-assemblés (CRMAA/CSACS), Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC, Canada H3C 3J7.
ACS Macro Lett. 2015 Oct 20;4(10):1158-1162. doi: 10.1021/acsmacrolett.5b00483. Epub 2015 Sep 28.
We demonstrate a unique combination of simultaneous top-down and bottom-up control of the morphology of block copolymer films by application of in situ optical irradiation during dip-coating. A light-addressable and block-selective small molecule, 4-butyl-4'-hydroxyazobenzene (BHAB), is introduced into a diblock copolymer of polystyrene and poly(4-vinylpyridine) (PS-P4VP) of 28.4 wt % P4VP via supramolecular chemistry, notably by hydrogen bonding to P4VP. We show that the spherical morphology of thin films dip-coated from a THF solution at slow withdrawal rates in the dark convert to cylindrical morphology when dip-coated under illumination. This is attributed to volume expansion of the P4VP/BHAB phase due to - photoisomerization combined with a light-induced increase in BHAB uptake in the film. The demonstrated photocontrol highlights the potential of dip-coating as a scalable film preparation method that can be easily coupled with external stimuli to direct nanostructured self-assembly in the films as solvent evaporates.
我们展示了一种独特的组合，即在浸涂过程中通过原位光辐照同时对嵌段共聚物薄膜的形态进行自上而下和自下而上的控制。一种可光寻址且具有嵌段选择性的小分子4-丁基-4'-羟基偶氮苯（BHAB），通过超分子化学方法，特别是通过与聚4-乙烯基吡啶（P4VP）形成氢键，被引入到P4VP含量为28.4 wt%的聚苯乙烯和聚4-乙烯基吡啶（PS-P4VP）二嵌段共聚物中。我们表明，在黑暗中以缓慢的提拉速度从四氢呋喃溶液中浸涂的薄膜的球形形态，在光照下浸涂时会转变为圆柱形形态。这归因于P4VP/BHAB相由于光异构化以及薄膜中光诱导的BHAB吸收增加而导致的体积膨胀。所展示的光控突出了浸涂作为一种可扩展的薄膜制备方法的潜力，该方法可以很容易地与外部刺激相结合，在溶剂蒸发时引导薄膜中的纳米结构自组装。
