Surfactants are widely utilized in various industries, but their amphiphilic nature poses an obstacle to the complete recycling of them from water or oil phases. It is a challenge to design a surfactant that has both good emulsification performance and aqueous-phase recyclable properties. In this paper, we report a novel aqueous-phase recyclable surfactant with multi-headgroups (CH-NH (CCOONa), di-UAPAba). Di-UAPAba can stabilize oil-in-water emulsions alone at pH ≥ 9 (≥0.3 mM), exhibiting excellent emulsification ability. After adding a trace amount of silica nanoparticles, CO switchable oil-in-dispersion emulsions were formed by di-UAPAba at extremely low concentrations (0.01 mM). Reversible demulsification/emulsification was achieved upon CO/N trigger. Moreover, di-UAPAba can be converted into zwitterionic di-UAPAza by bubbling CO, which entirely enters the aqueous phase with no surfactant residual in the oil phase. Consequently, the emulsions were reformed after di-UAPAba was completely recovered from the aqueous phase. The interfacial behavior of the surfactant and its aqueous recyclable mechanism was analyzed by molecular dynamics simulation. This study introduces a new type of aqueous-recyclable surfactants that can be beneficial in temporary emulsions for oil-soluble products where demulsification is necessary, such as in crude oil production, oil transportation, and multi-phase catalysis.

中文翻译：

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CO2 可转换的多头基表面活性剂，用于具有可重复使用水相的分散油乳液


表面活性剂广泛应用于各个行业，但其两亲性质对其从水相或油相中的完全回收造成了障碍。设计一种兼具良好乳化性能和水相可回收性能的表面活性剂是一个挑战。在本文中，我们报道了一种具有多头基的新型水相可回收表面活性剂（CH-NH（CCOONa），di-UAPAba）。 Di-UAPAba 可在 pH ≥ 9 (≥0.3 mM) 下单独稳定水包油乳液，表现出优异的乳化能力。添加微量二氧化硅纳米粒子后，通过极低浓度 (0.01 mM) 的 di-UAPAba 形成 CO 可转换的分散油乳液。 CO/N 触发后可实现可逆破乳/乳化。此外，通过通入CO，di-UAPAba可以转化为两性离子di-UAPAza，其完全进入水相，油相中没有表面活性剂残留。因此，在从水相中完全回收di-UAPAba后，乳液被重新形成。通过分子动力学模拟分析了表面活性剂的界面行为及其水循环机理。这项研究介绍了一种新型水性可回收表面活性剂，可用于需要破乳的油溶性产品的临时乳液，例如原油生产、石油运输和多相催化。