Zhang Wanqing, Binks Bernard P, Jiang Jianzhong, Cui Zhenggang
The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical & Material Engineering, Jiangnan University, 1800 Lihu Road, 214122, Wuxi, China.
Department of Chemistry, University of Hull, HU6 7RX, Hull, UK.
Angew Chem Int Ed Engl. 2023 Oct 16;62(42):e202310743. doi: 10.1002/anie.202310743. Epub 2023 Aug 31.
Retaining emulsions stable at high acidity and salinity is still a great challenge. Here, we report a novel multi-headgroup surfactant (C H -NH (C COOH) , di-UAPAc) which can be reversibly transformed among cationic, anionic and zwitterionic forms upon pH variation. Stable oil-in-dispersion (OID) emulsions in strong acidity (pH=2) can be co-stabilized by low concentrations of di-UAPAc and silica nanoparticles. High salinity at pH=2 improves the adsorption of di-UAPAc on silica particles through hydrogen bonding, resulting in the transformation of OID emulsions into Pickering emulsions. Moreover, emulsification/demulsification and interconversion between OID and Pickering emulsions together with control of the viscosity and droplet size can be triggered by pH. The present work provides a new protocol for designing surfactants for various applications in harsh aqueous media, such as strong acidity and high salinity, involved in oil recovery and sewerage treatments.
保持乳液在高酸度和高盐度下的稳定性仍然是一个巨大的挑战。在此，我们报道了一种新型的多头基表面活性剂（C₁₈H₃₇-NH-(C₂H₄COOH)₂，二-UAPAc），它可以在pH值变化时在阳离子、阴离子和两性离子形式之间可逆地转变。在强酸性（pH = 2）条件下，低浓度的二-UAPAc和二氧化硅纳米颗粒可以共同稳定稳定的分散油（OID）乳液。在pH = 2时的高盐度通过氢键作用改善了二-UAPAc在二氧化硅颗粒上的吸附，导致OID乳液转变为Pickering乳液。此外，pH值可以引发乳化/破乳以及OID乳液和Pickering乳液之间的相互转化，同时还能控制粘度和液滴大小。本工作为设计用于苛刻水性介质（如强酸性和高盐度）中各种应用的表面活性剂提供了一种新方案，这些应用涉及石油开采和污水处理。
