Preparation Of Organic-Inorganic Functional Hybrid Microcapsules From Pickering Emulsion Polymerization

Organic-inorganic hybrid microcapsules are new materials with special structures. The advantages of polymer materials and inorganic materials can be obtained by preparation of hybrid microcapsules. They have many potential applications, such as delivery systems, environmental protection and biochemical engineering. Therefore, poly(N-isopropylacrylamide)/silica hybrid capsules, poly (methacrylic acid) /silica hybrid capsules and magnetic chitosan composite hollow microspheres were prepared from Pickering emulsion in this study. The influence factors, formation mechanism and applications of these materials were studied. The main research works are summarized as follows:1. Poly(N-isopropyl acrylamide)/silica hybrid capsules (THRCs) were prepared from inverse Pickering emulsion polymerization route. The aqueous solution of N-isopropyl acrylamide and poly (N-isopropyl acrylamide) was emulsified into an oil phase containing divinyl benzene by sonication to obtain a water-in-oil (W/O) Pickering emulsion stabilized by KH-570 modified silica nanoparticles. And then the emulsion was polymerized to obtain the hybrid capsules. The average particle size of the capsules is about 7-10μm. The capsules wall consist of two layers:a solid particle layer and a temperature-responsive polymer layer, The as-synthesized capsules exhibit good temperature-responsive property whose phase-transition temperature is 27℃. The controlled release experiment at different temperature were also investigated. When the medium temperatures were 25℃and 45℃, the released percents of Rhodamine B from TRHCs were 25.7% and 70.9%, respectively.2. Poly(methacrylic acid)/silica hybrid capsules (PHRCs) were successfully prepared from inverse Pickering emulsion polymerization route using KH-570 modified silica nanoparticles as stabilizers, the aqueous solution of methacrylic acid as aqueous phase and liquid paraffin as oil phase. Then the emulsion was polymerized to obtain the hybrid capsules.The average particle size of the capsules is about 7-10μm. The capsules wall consist of two layers:a solid particle layer and a pH-responsive polymer layer, the thickness of the wall is about 1μm. The as-synthesized capsules exhibit good property. The controlled release experiment in different release medium was carried. When the medium were alkaline and acidic, the released percents of Rhodamine B from PRHCs were 15.0% and 98.4%, respectively.3. Magnetic chitosan composite microspheres were successfully synthesized in an inverse Pickering emulsion route using oleic acid modified nano-Fe3O4 particles as stabilizers. The aqueous solution of acetic acid and chitosan was emulsified into an oil phase by sonication to obtain a Pickering emulsion. The average size of the composite microspheres is 8μm, The tickness of the wall is about 80nm. The microspheres were charactered by FTIR and TG.