Univ. Limoges, CNRS, IRCER, UMR 7315, F-87000 Limoges, France.
Univ. Limoges, CNRS, IRCER, UMR 7315, F-87000 Limoges, France.
J Colloid Interface Sci. 2018 Jun 15;520:127-133. doi: 10.1016/j.jcis.2018.03.019. Epub 2018 Mar 7.
Pickering emulsions were prepared using wax and silica submicronic particles (650 nm), as a first step towards the synthesis of Janus particles. Surfactants added to silica particles control the emulsion stability and particles arrangement, i.e. their penetration depth into the wax and their ability to form a monolayer. Thus, a systematic study of surfactants is proposed.
Zeta potential measurements and sedimentation tests are conducted to evaluate interactions of two cationic (CTAB: hexadecyltrimethylammonium bromide and DDAB: didodecyldimethylammonium bromide) and two polymeric surfactants with silica surface. Surfactants affinity for the wax is estimated by contact angle measurements. Emulsions stability is compared to evaluate the ability of particles to stabilize wax droplets. Through microscopic analyses, the penetration depth into the wax is measured as well as the ability to form a monolayer or multilayers/aggregates.
All surfactants modify silica surface properties, but only CTAB and DDAB give stable Pickering emulsions. Because of a better affinity for the wax, DDAB presents the best characteristics for Janus particle synthesis, allowing a larger variation of particles penetration depth into the wax.
使用蜡和二氧化硅亚微米颗粒（650nm）制备了 Pickering 乳液，作为合成 Janus 颗粒的第一步。添加到二氧化硅颗粒中的表面活性剂控制乳液稳定性和颗粒排列，即它们进入蜡的穿透深度及其形成单层的能力。因此，提出了对表面活性剂的系统研究。
进行了动电位测量和沉降试验，以评估两种阳离子（CTAB：十六烷基三甲基溴化铵和 DDAB：双十二烷基二甲基溴化铵）和两种聚合物表面活性剂与二氧化硅表面的相互作用。通过接触角测量来估计表面活性剂对蜡的亲和力。通过比较乳液稳定性来评估颗粒稳定蜡滴的能力。通过微观分析，测量了进入蜡的穿透深度以及形成单层或多层/聚集体的能力。
所有表面活性剂都改变了二氧化硅表面的性质，但只有 CTAB 和 DDAB 能产生稳定的 Pickering 乳液。由于对蜡的亲和力更好，DDAB 为 Janus 颗粒合成提供了最佳特性，允许更大的颗粒穿透深度变化进入蜡。
