액체-액체 계면에 복합 박막층 형성을 통한 연성 콜로이드 안정화에 대한 연구

Abstract

Typical Pickering emulsions accumulate particles to form a robust colloidal layer at an immiscible liquid–liquid interface. However, if the particles are smaller than tens of nanometers, they have a tendency toward coming off from the interface, thereby destabilizing emulsion drops. To solve this problem, a technique that can make the adsorbed nanoparticles stay at the interface should be developed. This study introduces a practical method that allows us to obtain a mechanically stable Pickering emulsions; n-decane was emulsified to form an oil-in-water emulsion of which interface was stabilized with a complex colloidal layer consisting of 12 nm-sized silica nanoparticles, a poly(vinyl alcohol) binder, and an alkyl-chained silane coupling agent. We have found that in the conditions of high salinity, the emulsion drops attract each other and form an emulsion gel phase. However, even in such harsh conditions, the complex silica layer maintains its original structure at the interface, thus stabilizing the emulsion drop against coalescence.|This study introduces a practical method that allows us to provide a mechanically robust hybrid polyelectrolyte/silica thin shell on the uniform hydrogel particles. To fabricate these particles, first, monodisperse precursor emulsion drops generated in a microfluidic device were converted to hydrogel particles by photo-polymerization. The hydrogel particles were mainly composed of poly(ethylene glycol) diacrylate. Sodium 4-vinylbenzenesulfonate was also copolymerized to give negative charges on the surface. The layer-by-layer deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-vinylbenzenesulfonate) was carried out for surface treatment of the hydrogel particles. A thin silica layer was formed by reduction of silicate on the quaternized ammonium groups on the surface of hydrogel particles. It is expected that these complex hydrogel microparticles fabricated via the combined layer-by-layer assembly and silicification procedure will be useful for encapsulating living species as well as for storing with excellent viability (a demonstration experiment is under way).; This study introduces a practical method that allows us to provide a mechanically robust hybrid polyelectrolyte/silica thin shell on the uniform hydrogel particles. To fabricate these particles, first, monodisperse precursor emulsion drops generated in a microfluidic device were converted to hydrogel particles by photo-polymerization. The hydrogel particles were mainly composed of poly(ethylene glycol) diacrylate. Sodium 4-vinylbenzenesulfonate was also copolymerized to give negative charges on the surface. The layer-by-layer deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-vinylbenzenesulfonate) was carried out for surface treatment of the hydrogel particles. A thin silica layer was formed by reduction of silicate on the quaternized ammonium groups on the surface of hydrogel particles. It is expected that these complex hydrogel microparticles fabricated via the combined layer-by-layer assembly and silicification procedure will be useful for encapsulating living species as well as for storing with excellent viability (a demonstration experiment is under way).