Preparation And Properties Of Materials Based On Pickering Emulsion

Pickering emulsions are emulsions that stabilize multiphase systems with solid particles as emulsifiers,in which one liquid is dispersed in the form of droplets in another immiscible liquid.Compared with traditional emulsions,Pickering emulsions are more stable and can be widely used.Hydrogel is a three-dimensional network polymer that can absorb water and swell but not dissolve in water.It can be made into gel microspheres and microcapsules.Due to its special structure,it is widely used in the removal of pollutants and the encapsulation and controlled release of active substances.Combining Pickering emulsions with hydrogels will provide new ideas for the application research of Pickering emulsions.In this study,based on stable O/W and W/O/W Pickering emulsions,PANI-loaded O/W Pickering emulsion gel microspheres were first prepared by chemical cross-linking between free radicals.The W/O/W type Pickering emulsion-gel microcapsules wrapped with MB were prepared by physical cross-linking between ions,and their application properties under different influencing factors were studied respectively.The specific research contents of this paper are as follows:（1）Using the mixed solution of toluene and aniline as the organic phase,and a certain amount of mixed solution of hydrochloric acid and ammonium persulfate as the aqueous phase,polyaniline（PANI）powder was prepared by the interfacial polymerization method.The asprepared PANI was characterized by FTIR and SEM,and the PANI-loaded O/W Pickering emulsion was prepared with the PANI aqueous solution as the water phase.Then,the O/W type Pickering emulsion gel microspheres loaded with PANI with different diameters were prepared by chemical cross-linking method,and their adsorption properties were tested under different conditions.The results show that:when pH=3,T=35℃,the gel microspheres with a diameter of 0.5 cm have better adsorption effect on 100 mg/L MO dye,and the maximum adsorption capacity can reach 72.8 mg/g.In addition,by fitting the adsorption process,it is found that the adsorption is more in line with the Langmuir adsorption isotherm model and the pseudo-secondorder kinetic model.Since PANI contains amino and imino groups,this structure provides a large number of adsorption sites for the molecular chain,so PANI can pass through Electrostatic attraction,hydrogen bonding and π-π interaction interact with dye molecules to achieve the purpose of adsorbing dyes,so that the adsorption can proceed spontaneously.In addition,after five cycles of adsorption-desorption experiments,it was found that the removal rate of MO dye by the gel microspheres remained above 80%,indicating that the O/W type Pickering emulsion gel microspheres loaded with PANI had good recycling performance.（2）Based on the O/W Pickering emulsion loaded with PANI,the "two-step emulsification method" was used to prepare the W/O/W Pickering emulsion wrapped with MB,and the oilwater volume ratio,the mass fraction of different SiO₂ solid particles,etc.Factors affect the stability of the formed emulsion,and a W/O/W Pickering emulsion that can stably encapsulate MB was studied.Then,based on the W/O/W Pickering emulsion that stably encapsulates MB,a W/O/W Pickering emulsion with calcium alginate as the wall material and the water-soluble dye methylene blue as the core was prepared by physical cross-linking and curing method.The gel microcapsules of 1000 μm diameter were found to have an average water content of 48.54%,and the average bulk density of 1500 μm diameter microcapsules was 0.64 g/mL,and the microcapsules were moisture-resistant.Sex is good.The microcapsules were slowly released under different conditions.The experimental results showed that the gel microcapsules with a diameter of 1000 μm and a temperature of 35℃ were soaked in acid first,and then placed in water.This shows that the gel microcapsules prepared on the basis of Pickering emulsion have good sustained release performance.