Particle-stabilized emulsions that can respond to external stimuli have attracted significant concerns due to their intelligent-controlled stability, whereas particle-stabilized Pickering emulsions responding to multistimuli but based on biomass have been rarely reported. Here, a multistimuli-responsive Pickering emulsion was developed using the modified chitosan as stabilizer. Due to electrostatic attraction, Se-containing anionic surfactant, sodium 11-(butylselenyl)undecylsulfate (C₄SeC₁₁S), can bind with CS at an acidic pH and form CS–C₄SeC₁₁S complexes which can further self-associate to form micrometer-sized particles with the character of partially hydrophobicity. Therefore, at pH < pK_a, an oil-in-water Pickering emulsion can be formed using CS–C₄SeC₁₁S particles as stabilizers and can spontaneously respond to redox, ion, and pH. First, with the addition of oxidation, the hydrophilicity of C₄SeC₁₁S was enhanced, and thus, hydrophobic association of CS–C₄SeC₁₁S decreased, leading to the disruption of CS–C₄SeC₁₁S particles. Hence, the emulsion destabilized. The demulsification process is closely related with the dosage of oxidant and the oxidation time. Second, introduction of a competitive ion (e.g., CTAB) could break the binding between C₄SeC₁₁S and CS, leading to the disruption of particle emulsifier. Thereby, demulsification occurred. Third, with sequentially increasing/decreasing pH, the emulsion can be switched from stable to unstable and then to stable again accordingly. Such a unique pH-responsive behavior has never been discovered in other pH-responsive Pickering emulsions. All of the stimuli-responsive behaviors were reversible. Upon alternately adding oxidant/reductant, CTAB/C₄SeC₁₁S, or base/acid, the current emulsion can be reversibly switched off (destabilization) and on (stabilization). Such a Pickering emulsion may be a good candidate as a vehicle of functional ingredient.

中文翻译：

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含硒表面活性剂改性壳聚糖稳定的多刺激响应性匹克乳液

由于其智能控制的稳定性，可响应外部刺激的颗粒稳定的乳剂引起了广泛的关注，而很少响应基于生物质的多种刺激的颗粒稳定的Pickering乳剂。在这里，使用改性壳聚糖作为稳定剂，开发了一种多刺激响应的Pickering乳液。由于静电吸引，含硒的阴离子表面活性剂11-（丁基硒烯基）十一烷基硫酸钠（C ₄ SeC ₁₁ S）可以在酸性pH下与CS结合形成CS–C ₄ SeC ₁₁ S复合物，可以进一步自缔合形成具有部分疏水性的微米级颗粒。因此，在pH <p K _a时，可以使用CS–C ₄ SeC ₁₁ S颗粒作为稳定剂来形成水包油Pickering乳液，并且可以自发响应氧化还原，离子和pH。首先，通过添加氧化作用，C ₄ SeC ₁₁ S的亲水性得到增强，因此CS–C ₄ SeC ₁₁ S的疏水缔合作用降低，从而导致CS–C ₄ SeC ₁₁ S颗粒破裂。因此，乳液不稳定。破乳过程与氧化剂的用量和氧化时间密切相关。其次，引入竞争性离子（例如CTAB）可能会破坏C ₄ SeC ₁₁之间的结合S和CS，导致颗粒乳化剂的破坏。由此，发生破乳。第三，随着pH的依次升高/降低，乳液可从稳定状态转变为不稳定状态，然后相应地再次稳定。在其他pH响应性Pickering乳液中从未发现过这种独特的pH响应行为。所有的刺激反应行为都是可逆的。交替添加氧化剂/还原剂，CTAB / C ₄ SeC ₁₁ S或碱/酸后，可以可逆地关闭（稳定化）和开启（稳定化）本乳液。这种Pickering乳液可以作为功能成分的媒介物很好的选择。