Björkegren Sanna, Freixiela Dias Maria Costa Artur, Lundahl Kristina, Nordstierna Lars, Palmqvist Anders
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Nouryon Pulp and Performance Chemicals AB, SE-445 80 Bohus, Sweden.
Langmuir. 2020 Mar 10;36(9):2357-2367. doi: 10.1021/acs.langmuir.9b03648. Epub 2020 Mar 2.
In this study, the emulsification performance of functionalized colloidal silica is explored with the aim to achieve phase inversion of particle-stabilized (Pickering) emulsion systems. An increased understanding of inversion conditions can facilitate surfactant-free emulsion fabrication and expand its use in industrial applications. Phase inversion was achieved by adjusting the temperature but without changing the composition of the emulsion formulation. Silica nanoparticles modified with hydrophobic propyl groups and hydrophilic methyl poly(ethylene)glycol (mPEG) groups are used as emulsifiers, enabling control of the wettability of the particles and exploration of phase inversion phenomena, the latter due to the thermoresponsiveness of the attached PEG chains. The phase inversion conditions as well as the reversibility of the emulsion systems were examined at varying electrolyte concentrations and pH values of the suspensions. Transitional phase inversions, from oil-in-water and water-in-oil and back, were observed in functionalized silica particle-stabilized butanol emulsions at distinct temperatures. The phase inversion temperature was affected by electrolyte concentration and pH conditions due to salting-out effects, PEG-silica interactions, and the effects of the particle surface charge. Investigations of phase inversion conditions, temperature, and hysteresis effects in Pickering emulsions can improve the theoretical understanding of these phenomena and facilitate the implementation of low-energy emulsion preparation.
在本研究中，探索了功能化胶体二氧化硅的乳化性能，目的是实现颗粒稳定（皮克林）乳液体系的相转变。对转变条件的深入理解有助于无表面活性剂乳液的制备，并扩大其在工业应用中的用途。通过调节温度实现了相转变，但未改变乳液配方的组成。用疏水性丙基和亲水性甲基聚（乙二醇）（mPEG）基团改性的二氧化硅纳米颗粒用作乳化剂，能够控制颗粒的润湿性并探索相转变现象，后者归因于连接的PEG链的热响应性。在不同的电解质浓度和悬浮液pH值下，研究了乳液体系的相转变条件以及可逆性。在不同温度下，在功能化二氧化硅颗粒稳定的丁醇乳液中观察到了从水包油和油包水再返回的过渡相转变。由于盐析效应、PEG-二氧化硅相互作用以及颗粒表面电荷的影响，相转变温度受电解质浓度和pH条件的影响。对皮克林乳液中的相转变条件、温度和滞后效应的研究可以提高对这些现象的理论理解，并促进低能耗乳液制备的实施。
