Institut des Sciences Moléculaires, ENSCBP, Université de Bordeaux , 16 Av. Pey Berland, 33607 Pessac Cedex, France.
Langmuir. 2013 Oct 8;29(40):12367-74. doi: 10.1021/la402921b. Epub 2013 Sep 27.
This work reports a new evidence of the versatility of soft responsive microgels as stabilizers for Pickering emulsions. The organization of microgels at the oil-water interface is a function of the preparation pathway. The present results show that emulsification energy can be used as a trigger to modify microgel deformation at the oil-water interface and their packing density: high shear rates bring strong flattening of the microgels, whereas low shear rates lead to dense monolayers, where the microgels are laterally compressed. As a consequence, the resulting emulsions have opposite behavior in terms of flocculation, which arises from bridging between neighboring drops and is strongly dependent on their surface coverage. This strategy can be applied to any microgel which can sufficiently adsorb at low shear rates, i.e. small microgels or lightly cross-linked ones. The control of the organization of microgels at the interface does not only modify emulsion end-use properties but also constitutes a new tool for the development of Janus-type microgels, obtained by chemical modification of the adsorbed microgels.
这项工作报道了软响应性微凝胶作为 Pickering 乳液稳定剂的多功能性的新证据。微凝胶在油水界面的组织是制备途径的函数。目前的结果表明,乳化能量可用作触发因素来改变油水界面处微凝胶的变形和它们的堆积密度:高剪切速率会强烈地使微凝胶变平,而低剪切速率会导致微凝胶的紧密单层,在这种情况下,微凝胶会受到侧向压缩。因此,由此产生的乳液在絮凝方面表现出相反的行为,这是由于相邻液滴之间的桥接引起的,并且强烈依赖于它们的表面覆盖率。这种策略可应用于任何在低剪切速率下能够充分吸附的微凝胶,即小的微凝胶或轻度交联的微凝胶。控制微凝胶在界面上的组织不仅可以改变乳液的最终用途性能,而且还构成了开发 Janus 型微凝胶的新工具,Janus 型微凝胶是通过吸附的微凝胶的化学修饰获得的。