Guan Xin, Liu Yang, Wan Zhili, Steve Tse Ying-Lung, Ngai To
Department of Chemistry, The Chinese University of Hong Kong Shatin N. T. Hong Kong China
School of Food Science and Technology, South China University of Technology Guangzhou 510640 China.
Chem Sci. 2022 Apr 26;13(21):6205-6216. doi: 10.1039/d2sc01082h. eCollection 2022 Jun 1.
Microgels are extremely interfacially active and are widely used to stabilize emulsions. However, they are commonly used to stabilize oil-in-water emulsions due to their intrinsic hydrophilicity and initially dispersed in water. In addition, there have been no attempts to control microgel structural layers that are formed at the interface and as a result it limits applications of microgel in advanced materials. Here, we show that by introducing octanol into poly(-isopropylacrylamide--methacrylic acid) (PNIPAM--MAA) microgels, octanol-swollen microgels can rapidly diffuse from the initially dispersed oil phase onto the water droplet surface. This facilitates the formation of microgel-laden interfacial layers with strong elastic responses and also generates stable inverse water-in-oil Pickering emulsions. These emulsions can be used as templates to produce microgel colloidosomes, herein termed 'microgelsomes', with shells that can be fine-tuned from a particle monolayer to a well-defined bilayer. The microgelsomes can then be used to encapsulate and/or anchor nanoparticles, proteins, vitamin C, bio-based nanocrystals or enzymes. Moreover, the programmed release of these substances can be achieved by using ethanol as a trigger to mediate shell permeability. Thus, these reconfigurable microgelsomes with a microgel-bilayer shell can respond to external stimuli and demonstrate tailored properties, which offers novel insights into microgels and promise wider application of Pickering emulsions stabilized by soft colloids.
微凝胶具有极高的界面活性,被广泛用于稳定乳液。然而,由于其固有的亲水性且最初分散于水中,它们通常用于稳定水包油乳液。此外,此前尚未有人尝试控制在界面处形成的微凝胶结构层,因此这限制了微凝胶在先进材料中的应用。在此,我们表明,通过将辛醇引入聚(N-异丙基丙烯酰胺-甲基丙烯酸)(PNIPAM-MAA)微凝胶中,辛醇溶胀的微凝胶能够从最初分散的油相迅速扩散到水滴表面。这有助于形成具有强弹性响应的富含微凝胶的界面层,还能生成稳定的反相油包水皮克林乳液。这些乳液可用作模板来制备微凝胶胶体囊泡,在此称为“微凝胶体”,其外壳可从颗粒单层精细调节至明确的双层。然后,微凝胶体可用于封装和/或锚定纳米颗粒、蛋白质、维生素C、生物基纳米晶体或酶。此外,通过使用乙醇作为触发剂来调节外壳渗透性,可以实现这些物质的程序释放。因此,这些具有微凝胶双层外壳的可重构微凝胶体能够响应外部刺激并展现出定制特性,这为微凝胶提供了新的见解,并有望使软胶体稳定的皮克林乳液得到更广泛的应用。