【摘要】 以正癸烷为油相,纳米Si O₂和十四烷基二乙烯三胺(C₁₄DETA)为乳化剂,制备了CO₂响应性O/W型Pickering乳状液。交替通入CO₂和N₂,该乳状液在25℃下实现了"开（稳定）"和"关（不稳定）"之间的多次转换。通入CO₂时,C₁₄DETA质子化成C₁₄DETA-CO₂,通过静电作用吸附至带负电的Si O₂颗粒表面,产生原位疏水作用,使其转变为表面活性颗粒,从而稳定乳状液;通入N₂时,C₁₄DETA-CO₂去质子化为C₁₄DETA,原位疏水作用解除,导致乳状液完全破乳。通过研究确定乳化的较佳条件:油水体积比为1∶1,纳米Si O₂的质量分数为0.05%,C₁₄DETA-CO₂浓度为2×10^-3 mol/L。与C₁₄DETA稳定的乳状液对比,Pickering乳状液中表面活性剂使用量更少,稳定性更强。更多还原

【Abstract】 The CO₂-triggered O/W Pickering emulsion was prepared with Si O₂ nanoparticles and tetradecyldiethylenetriamine (C₁₄DETA) as emulsifiers and n-decane as oil phase.At 25℃,the emulsion could be smartly switched"on （stable）"and"off （unstable）"by bubbling CO₂ and N₂ alternately.C₁₄DETA was protonated into C₁₄DETA-CO₂ by bubbling CO₂,and then adsorbed to the surface of negatively charged Si O₂particles through electrostatic interaction,resulting in in-situ hydrophobic effect and transforming Si O₂ particles into surface-active particles and thus stabilizing the emulsion.However,C₁₄DETA-CO₂ was deprotonated into C₁₄DETA by bubbling N₂,which induced the elimination of in-situ hydrophobic effect,thus leading to complete demulsification of the emulsion.The emulsifying conditions were optimized:the volume ratio of oil/water was1∶1;the mass fraction of Si O₂ particles was 0.05%and the concentration of C₁₄DETA-CO₂ was 2×10^-3 mol/L.The Pickering emulsion needed less surfactant and had stronger stability than the emulsion with C₁₄DETA as the surfactant.更多还原