Meng Yuwen, Nicolai Taco
Le Mans Université, IMMM UMR-CNRS 6283, 72085, cedex 9, Le Mans, France.
J Colloid Interface Sci. 2023 May 15;638:506-512. doi: 10.1016/j.jcis.2023.02.006. Epub 2023 Feb 4.
Water-in-water (W/W) emulsions formed by mixing incompatible polymers in aqueous solution can in some cases be stabilized by adding particles that adsorb spontaneously at the W/W interface. The importance of the contact angle of the particles with the interface on the stability of W/W emulsions is still an outstanding issue. We hypothesize that if the contact angle with the continuous phase is smaller than 90°, particles can bridge dispersed droplets, which enhances the stability of the emulsion.
The W/W emulsions consisted of a dispersed poly(ethylene oxide) (PEO) phase in a continuous dextran phase or vice versa. Gelatin microgels were added and their contact angle was varied by varying the pH. The morphology during aging was observed by microscopy.
The contact angle of the microgels with the PEO phase varied between 110° close to neutral pH and 0° at pH 3 and pH 11. The W/W emulsions were stable only when the contact angle with the continuous phase was smaller than 90°. In this case, microgels could form bridges between dispersed droplets creating a network of droplets.
通过在水溶液中混合不相容聚合物形成的水包水（W/W）乳液，在某些情况下可以通过添加能在W/W界面自发吸附的颗粒来实现稳定。颗粒与界面的接触角对W/W乳液稳定性的重要性仍是一个未解决的问题。我们推测，如果与连续相的接触角小于90°，颗粒能够桥接分散的液滴，从而增强乳液的稳定性。
W/W乳液由在连续葡聚糖相中的分散聚环氧乙烷（PEO）相组成，反之亦然。添加了明胶微凝胶，并通过改变pH值来改变其接触角。通过显微镜观察老化过程中的形态。
微凝胶与PEO相的接触角在接近中性pH时为110°，在pH 3和pH 11时为0°。只有当与连续相的接触角小于90°时，W/W乳液才是稳定的。在这种情况下，微凝胶可以在分散的液滴之间形成桥接，形成液滴网络。
