Reversible tuning of wetting behavior of polymer surface with responsive polymer brushes
Reversible tuning of wetting behavior of polymer surface with responsive polymer brushes
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DOI：
10.1021/la0343573
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发表时间：
2003-09-16
期刊：
影响因子：
3.9
通讯作者：
Stamm, M
中科院分区：
文献类型：
--
作者：
Motornov, M;Minko, S;Stamm, M
我们发展了一条在聚酰胺（PA-6，PA-6 I，PA-66）基底上通过“接枝”方法制备混合刷状层的路线。PA基板通过NH3等离子体官能化。自由基聚合的偶氮引发剂共价键合到官能化的PA表面。采用两步接枝法，第一步接枝聚苯乙烯，第二步接枝聚（2-乙烯基吡啶）。我们发现在Si晶片上和PA衬底上接枝之间存在显着差异。从PA表面“接枝”导致膜的表面粗糙度显著增加，这可以通过在PA的溶胀表面层中接枝来解释。由于这种效应，我们发现了大量的接枝聚合物，即使在未官能化的PA基板上，这是通过链转移反应接枝解释。合成的混合聚合物刷形成响应涂层，其在暴露于选择性溶剂时由于横向和纵向相分离之间的相互作用而切换其形态。形貌的变化影响着电刷表面成分和表面能态的变化。我们在PA织物的表面上执行相同的接枝程序。在这种情况下，切换行为被材料的纹理放大：具有混合刷的织物的润湿性从完全润湿切换到高度疏水状态（150度水接触角）。
We develop the route to fabricate mixed brushlike layers on polyamide substrates (PA-6, PA-6I, PA-66) by the "grafting from" approach. The PA substrates were functionalized by NH3 plasma. The azo initiator of radical polymerization was covalently bound to the functionalized PA surface. A two-step grafting procedure was applied to graft polystyrene in the first step and poly(2-vinylpyridine) in the second step. We found remarkable differences between grafting on Si wafers and on the PA substrates. "Grafting from" the PA surface results in a dramatic increase of the surface roughness of the film which can be explained by grafting in a swollen surface layer of PA. Because of this effect, we found a substantial amount of grafted polymers even on not functionalized PA substrates, which was explained by grafting via chain transfer reaction. The synthesized mixed polymer brushes form responsive coatings which switch their morphology due to the interplay between lateral and vertical phase segregation upon exposure to selective solvent. The switching of morphology affects the change of the surface composition of the brushes and their surface energetic state. We performed the same grafting procedure on the surface of PA fabric. In this case the switching behavior was amplified by the texture of the material: wettability of the fabric with the mixed brush was switched from complete wetting to highly hydrophobic state (150degrees water contact angle).