In blends of chemically distinct polymers, the surface is usually enriched by the polymer with the lowest surface energy. Herein, we show that when “high energy” bottlebrush copolymers having an approximately equimolar mixture of polystyrene (PS) and poly(2-vinylpyridine) (P2VP) side chains are blended with “low energy” linear PS, the bottlebrush copolymer can enrich the free surface despite an estimated 15% gain in surface energy. This wetting reversal process is mediated by a strong entropic preference for the highly branched bottlebrush architecture at the surface of the blend. The high-energy surface forms spontaneously during film casting when the linear PS chains are much longer than the bottlebrush side chains and is stable through thermal annealing when the lengths of PS side chains, P2VP side chains, and linear PS are optimized. This work demonstrates that for a given commodity polymer, the library of candidate chemistries for the design of surface-active polymer additives is much broader than previously known.

中文翻译：

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Bottlebrush 共聚物和线性均聚物共混物中的润湿反转


在化学性质不同的聚合物的共混物中，表面通常由表面能最低的聚合物富集。在本文中，我们表明，当具有聚苯乙烯 （PS） 和聚（2-乙烯基吡啶）（P2VP） 侧链的近似等摩尔混合物的“高能”bottlebrush 共聚物与“低能”线性 PS 混合时，尽管表面能估计增加了 15%，但 bottlebrush 共聚物可以富集自由表面。这种润湿反转过程是由混合物表面高度支化的瓶刷结构的强烈熵偏好介导的。当线性 PS 链比瓶刷侧链长得多时，高能表面在薄膜流延过程中自发形成，当 PS 侧链、P2VP 侧链和线性 PS 的长度得到优化时，通过热退火保持稳定。这项工作表明，对于给定的商品聚合物，用于设计表面活性聚合物添加剂的候选化学库比以前已知的要广泛得多。