The molecular composition of polymer blend surfaces defines properties such as adhesion, wetting, gloss, and biocompatibility. The surface composition often differs from the bulk because of thermodynamic effects or modification. Mixtures of colloids and linear polymers in a common solvent are often used to deposit films for use in encapsulants, inks, coatings, and adhesives. However, means to control the nonequilibrium surface composition are lacking for these systems. Here we show how the surface composition and hydrophilicity of a film deposited from a bimodal mixture of linear polymers and colloids in water can be adjusted simply by varying the evaporation rate. Ion beam analysis was used to quantify the extent of stratification of the linear polymers near the surface, and the results are in agreement with a recent diffusiophoretic model. Because our approach to stratification relies solely on diffusiophoresis, it is widely applicable to any system deposited from colloids and nonadsorbing polymers in solution as a means to tailor surface properties.

中文翻译：

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胶体薄膜中聚合物的扩散泳驱动分层

聚合物共混物表面的分子组成决定了附着力、润湿性、光泽度和生物相容性等特性。由于热力学效应或改性，表面组成通常与本体不同。胶体和线性聚合物在普通溶剂中的混合物通常用于沉积薄膜，用于密封剂、油墨、涂料和粘合剂。然而，这些系统缺乏控制非平衡表面组成的方法。在这里，我们展示了如何通过改变蒸发速率来简单地调整由线性聚合物和胶体在水中的双峰混合物沉积而成的薄膜的表面组成和亲水性。离子束分析用于量化表面附近线性聚合物的分层程度，结果与最近的扩散泳模型一致。