Abstract Emulsions have been widely applied in subterranean enhanced oil recovery processes, cosmetics and chemistry engineering fields, etc. Current research interests are focusing on improving the stability of emulsion by involving surfactants or colloidal materials. This work aims to enhance the emulsion stabilization by introducing silica nanoparticles (SNP) surface-hydrophobilized/hydrophilized by adding dimethyldodecylamine oxide (OA-12) and to reveal the dynamic behaviors of such composites on the liquid–liquid interface. The synergistic effect between SNPs and OA-12 in solution and on oil/water interface were studied by measuring the zeta potential, interfacial rheology and emulsion viscoelastic rheology, etc. It was found that the oil/water interface viscoelastic modulus are augmented by modified silica nano-particles and at the same time emulsions acquired significant long-time stability. Furthermore, phase transformation was induced with the increase of the concentration ratio between OA-12 and silica nano-particle, the emulsion type change from o/w, then to w/o and back to o/w. It is suggested that the inversions are induced by the mounting adsorption of OA-12 molecules on SNPs, which changes the hydrophilic-lipophilic balance of particle surfaces.

中文翻译：

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在正庚烷/水界面用二甲基十二烷基胺氧化物修饰二氧化硅纳米颗粒的乳液行为控制和稳定性研究

摘要 乳液已广泛应用于地下提高采收率工艺、化妆品和化学工程等领域。目前的研究兴趣集中在通过加入表面活性剂或胶体材料来提高乳液的稳定性。这项工作旨在通过添加二甲基十二烷基胺氧化物（OA-12）引入二氧化硅纳米粒子（SNP）表面疏水化/亲水化来增强乳液稳定性，并揭示此类复合材料在液-液界面上的动态行为。通过测量zeta电位、界面流变学和乳液粘弹性流变学等，研究了SNPs与OA-12在溶液中和油/水界面上的协同作用。结果表明，改性二氧化硅纳米颗粒提高了油/水界面粘弹性模量，同时乳液获得了显着的长期稳定性。此外，随着OA-12与二氧化硅纳米颗粒之间的浓度比的增加，相变诱导，乳液类型从o/w变化，然后变为w/o，再回到o/w。这表明反转是由 OA-12 分子在 SNP 上的安装吸附引起的，这改变了颗粒表面的亲水亲油平衡。