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Different cationic surfactants-modified silica nanoparticles for Pickering emulsions
Journal of Molecular Liquids ( IF 6 ) Pub Date : 2019-07-09 , DOI: 10.1016/j.molliq.2019.111341
Xiao-Qian Wei , Wan-Ju Zhang , Lu Lai , Ping Mei , Li-Mei Wu , Yan-Qun Wang

The effects of cationic surfactants on the properties of Pickering emulsions stabilized by silica nanoparticles (nano-SiO2) were investigated. The zeta potential, three-phase contact angle (θ), and dynamic interfacial tension (DIT) were measured to analyze the interaction between hydrophilic nano-SiO2 and four different cationic surfactants (i.e., dodecyltrimethylammonium bromide [DTAB], bis-quaternary ammonium salts [BQAS-12], multiple quaternary ammonium salts [MQAS-12], and dimethyldioctadecylammonium bromide [DDAB-18]). All these surfactants can naturally improve the stability of Pickering emulsions induced by hydrophilic nano-SiO2. The nano-SiO2/MQAS-12 mixtures exhibited the best ability to stabilize the O/W emulsions, followed by nano-SiO2/BQAS-12 mixtures. The nano-SiO2/DDAB-18 mixtures can induce emulsion inversion from O/W to W/O. All emulsions exhibited excellent salt tolerance and acid-base resistance properties. Determining the zeta potential showed that nano-SiO2 had the highest negative charge at the pH of 9.5. Thus, the surfactant molecules can be adsorbed remarkably on the nano-SiO2 surface. Modification with different cationic surfactants can significantly increase the θ value of nano-SiO2, but the bilayers for DTAB-12, BQAS-12, and MQAS-12, except for DDAB-18, were adsorbed. DIT curves indicated that competitive adsorption of the surfactants occurred between the oil/water interface and nano-SiO2 surface. The competitive adsorption of MQAS-12 was stronger than those of BQAS-12 and DTAB-12. The nano-SiO2/DDAB-18 mixture had an apparent induction region and required a considerable amount of time to reach equilibrium. The modified nano-SiO2 was also not adsorbed in the oil/water interface spontaneously, which may be due to the large size of particles compared with small surfactant molecules.



中文翻译:

用于Pickering乳液的不同阳离子表面活性剂改性的二氧化硅纳米粒子

研究了阳离子表面活性剂对二氧化硅纳米颗粒(纳米SiO 2)稳定的Pickering乳液性能的影响。测量了ζ电势,三相接触角(θ)和动态界面张力(DIT),以分析亲水性纳米SiO 2与四种不同阳离子表面活性剂(即十二烷基三甲基溴化铵[DTAB],双季铵盐)之间的相互作用。盐[BQAS-12],多种季铵盐[MQAS-12]和二甲基二十八烷基溴化铵[DDAB-18])。所有这些表面活性剂都可以自然地改善亲水性纳米SiO 2诱导的Pickering乳液的稳定性。纳米SiO 2/ MQAS-12混合物表现出最佳的稳定O / W乳液的能力,其次是纳米SiO 2 / BQAS-12混合物。纳米SiO 2 / DDAB-18混合物可引起乳液从O / W转化为W / O。所有乳液均表现出优异的耐盐性和耐酸碱性能。测定ζ电势表明,纳米SiO 2在9.5的pH下具有最高的负电荷。因此,表面活性剂分子可以显着地吸附在纳米SiO 2表面上。用不同的阳离子表面活性剂改性可显着提高纳米SiO 2θ,但吸附了DTAB-12,BQAS-12和MQAS-12的双层膜,但DDAB-18除外。DIT曲线表明,表面活性剂的竞争性吸附发生在油/水界面与纳米SiO 2表面之间。MQAS-12的竞争性吸附作用强于BQAS-12和DTAB-12。纳米SiO 2 / DDAB-18混合物具有明显的诱导区,需要大量时间才能达到平衡。改性的纳米SiO 2也没有自发地吸附在油/水界面中,这可能是由于与小的表面活性剂分子相比,颗粒尺寸较大。

更新日期:2019-07-09
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