He Runna, Sun Shuangqing, Cui Jianpeng, Chi Mingshuo, Wang Zhikun, Hu Songqing
School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China.
Institute of Advanced Materials, China University of Petroleum (East China), Qingdao 266580, China.
Phys Chem Chem Phys. 2023 Sep 27;25(37):25780-25788. doi: 10.1039/d3cp03400c.
In recent years, Pickering emulsifiers have been widely used in various production fields due to their excellent structural stability, biocompatibility and environmental friendliness. For some applications, it is required that the emulsifier can quickly respond to environmental stimuli and control the transition between stable and unstable emulsions. In this paper, we report a novel composite Pickering emulsifier with FeO as the core and magnetic response recognition body, silica as the intermediate protective layer, and chitosan (CS) of different molecular weights to endow solid particles with surface activity and pH-responsive properties. This emulsifier can stabilize the emulsion in the emulsion system with deionized water as the aqueous phase and liquid paraffin as the oil phase and can control the demulsification of the formed emulsion under the dual pH/magnetic stimulation. The experimental results show that FeO@SiO@CS has good paramagnetism and pH responsiveness. The particle size of the composite emulsifier nanoparticles is between 90 nm and 120 nm, and the best stabilizing effect of the emulsion is achieved when the dosage is 0.5 wt%. In the pH range of 3-11, the emulsifier can rapidly demulsify a stable paraffin oil-water emulsion system under the action of a magnetic field of strength 0.4 T. The pH response of the emulsifier is as follows: when pH ≤ 2, the system can form a stable emulsion, which is composed of fully protonated chitosan as a free chain segment and FeO@SiO. Emulsion stabilization was achieved with monolithic FeO@SiO@CS as an emulsifier at pH > 2, and demulsification was achieved at pH ≈ p (CS) at 298 K. The research in this paper can provide a feasible idea and synthesis method for the preparation of organic-inorganic composite structure emulsifier.
近年来，皮克林乳化剂因其优异的结构稳定性、生物相容性和环境友好性而被广泛应用于各个生产领域。对于某些应用，要求乳化剂能够快速响应环境刺激并控制稳定乳液和不稳定乳液之间的转变。在本文中，我们报道了一种新型复合皮克林乳化剂，其以FeO为核心和磁响应识别体，二氧化硅为中间保护层，以及不同分子量的壳聚糖（CS），以使固体颗粒具有表面活性和pH响应特性。这种乳化剂可以在以去离子水为水相、液体石蜡为油相的乳液体系中稳定乳液，并能在pH/磁双重刺激下控制所形成乳液的破乳。实验结果表明，FeO@SiO@CS具有良好的顺磁性和pH响应性。复合乳化剂纳米颗粒的粒径在90nm至120nm之间，当用量为0.5wt%时可实现最佳的乳液稳定效果。在pH值为3 - 11的范围内，该乳化剂在强度为0.4T的磁场作用下可使稳定的石蜡油 - 水乳液体系快速破乳。该乳化剂的pH响应如下：当pH≤2时，体系可形成稳定乳液，其由完全质子化的壳聚糖作为自由链段和FeO@SiO组成。在pH>2时，以整体的FeO@SiO@CS作为乳化剂可实现乳液稳定，在298K下当pH≈p(CS)时实现破乳。本文的研究可为有机 - 无机复合结构乳化剂的制备提供可行的思路和合成方法。
