基于界面反应的液滴破裂现象制备油包水型纳米乳液

摘要

报道了一种利用油水界面反应导致液滴界面失稳并破裂、从而简便可控地制备纳米级油包水型(W/O)乳液液滴并用于活性物质包载的新方法.采用氢氧化钠水溶液为分散相、含有油酸的苯甲酸苄酯溶液为连续相,通过氢氧化钠和油酸在水/油界面反应生成具有更好界面稳定性的油酸钠以降低界面张力,从而导致界面失稳使得液滴破裂,实现了对W/O纳米乳液的可控制备.利用界面张力仪验证了反应过程对液滴界面张力的影响,并用高速摄像显微系统观察研究了液滴的微观破裂过程.系统考察了分散相液滴中氢氧化钠含量、分散相液滴黏度以及连续相中油酸含量对所制得的纳米液滴粒径的影响规律.同时,通过在分散相中加入活性物质,方便地实现了活性物质在W/O纳米乳液内的有效包封.%A new strategy based on interfacial-reaction-induced droplet-division for facile and controllable preparation of water-in-oil(W/O)nano-emulsions for encapsulation of actives was proposed. Aqueous solution containing the sodium hydroxide,and the mixture of the benzyl benzoate and the oleic acid,were respectively used as the dispersed phase and the continuous phase. The sodium hydroxide and the oleic acid could react at the W/O interface and produce the sodium oleate with more stable interface,which reduced the interfacial tension and made the droplet interface unstable,thus leading to the droplet division. As a result,W/O nano-emulsions were generated. An interfacial tensiometer was used to determine the interfacial tension decrease during the reaction process,and a high-speed camera was used to record the droplet-division process. The effects of NaOH content and viscosity of the droplet as well as the OA content of the continuous phase on the sizes of nano-emulsion droplets were systematically studied. Effective encapsulation of actives in the W/O nano-emulsions was achieved by simply adding the actives into the dispersed phase.