Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, South Yorkshire, U. K.
ACS Appl Mater Interfaces. 2022 Aug 31;14(34):39548-39559. doi: 10.1021/acsami.2c09910. Epub 2022 Aug 19.
Well-defined block copolymers have been widely used as emulsifiers, stabilizers, and dispersants in the chemical industry for at least 50 years. In contrast, nature employs amphiphilic proteins as polymeric surfactants whereby the spatial distribution of hydrophilic and hydrophobic amino acids within the polypeptide chains is optimized for surface activity. Herein, we report that polydisperse statistical copolymers prepared by conventional free-radical copolymerization can provide superior foaming performance compared to the analogous diblock copolymers. A series of predominantly (meth)acrylic comonomers are screened to identify optimal surface activity for foam stabilization of aqueous ethanol solutions. In particular, all-acrylic statistical copolymers comprising trimethylhexyl acrylate and poly(ethylene glycol) acrylate, P(TMHA--PEGA), confer strong foamability and also lower the surface tension of a range of ethanol-water mixtures to a greater extent than the analogous block copolymers. For ethanol-rich hand sanitizer formulations, foam stabilization is normally achieved using environmentally persistent silicone-based copolymers or fluorinated surfactants. Herein, the best-performing fully hydrocarbon-based copolymer surfactants effectively stabilize ethanol-rich foams by a mechanism that resembles that of naturally-occurring proteins. This ability to reduce the surface tension of low-surface-energy liquids suggests a wide range of potential commercial applications.
具有明确结构的嵌段共聚物作为乳化剂、稳定剂和分散剂在化学工业中已经应用了至少 50 年。相比之下，自然界利用两亲性蛋白质作为聚合物表面活性剂，通过这种方式，多肽链内亲水和疏水氨基酸的空间分布被优化以提高表面活性。在此，我们报告称，通过传统自由基共聚制备的多分散统计共聚物与类似的嵌段共聚物相比，可以提供更优异的发泡性能。筛选了一系列主要的（甲基）丙烯酸酯共聚单体，以确定对水醇溶液稳定泡沫的最佳表面活性。特别是包含三羟甲基己基丙烯酸酯和聚乙二醇丙烯酸酯的全丙烯酸统计共聚物 P(TMHA-PEGA)，具有很强的发泡能力，并且还能更大程度地降低一系列乙醇-水混合物的表面张力，比类似的嵌段共聚物更有效。对于富含乙醇的洗手液配方，通常使用环境持久性的硅基共聚物或含氟表面活性剂来稳定泡沫。在此，性能最佳的全碳氢化合物共聚物表面活性剂通过类似于天然存在的蛋白质的机制有效地稳定富含乙醇的泡沫。这种降低低表面能液体表面张力的能力表明其具有广泛的潜在商业应用。
