The Construction Of PoPD Capsules Based On Pickering Emulsion And Study Of Their Stability

Self-assembly of colloidal particles at the oil/water interface is a n effective bottom-up method for preparing functional microcapsules.Pickering emulsion is a stable two-phase stable system where solid particles are us ed as the emulgator instead of traditional surfactant molecules which can be attached to the surface of the capsule.Pickering emulsions have better thermodynamic stability and the shape of the capsules is more controllable.In the formation of Pickering e mulsion,particles with appropriate wettability can spontaneously gathered on the surface of oil/water boundary to prepare functional microcapsules by gelation or polymerization with the solvent as the kernel.Such functional microcapsules play an important role in drug encapsulation,drug slow release and catalysis fields.PoPD polymer has good conductivity,and its polymerization process can be realized by mixing with oxidant at room temperature.The polymerization process is simple with controllable shape and batch production.Based on these fact,Pickering emulsion was taken as the reaction system in this thesis,and the PoPD capsules were prepared by in situ self-assembly at the interface between oil and water,which can be potentially applied in drug d elivery,catalysis and energy storing.In this thesis poly?o-phenylendiamine?polymer and the formation of self-assembled fibers were prepared and studied with o-phenylendiamine as the monomer and FeCl₃ as oxidant.The influence of different reaction con centrations of monomer and different concentrations of oxidant were firstly studied for the PoPD self-assembly behavior.Different sizes of the PoPD fiber were fabricated by adjusting the concentrations of reaction monomer and Fe Cl 3,stirring speed and reaction temperature.The key factors and how the factors influence the fiber aggregation and self-assembly process were determined.Afterwards,the self-assembly PoPD fibers were formed in situ at the oil-water interface along with the formation of capsules in Pickering emulsion system with PoPD fibers cladding around the capsules as the emulsifier in the capsule emulsion system.Finally,the effects of monomer concentration,FeCl₃ concentration,stirring speed and reaction temperature on the formation and size of the capsules were also studied in the thesis.The stability of PoPD capsule in emulsion was investigated in the following 5 days after the PoPD capsules were formed.The 5-days stability study of the PoPD capsules revealed that the PoPD capsules at condition of 0.0049 mol/L FeCl₃-0.1850mol/Lo PD-900rpm-25? showed the best stability and at the same time,the average size and the numbers of the PoPD capsules stay stable in the following 5 days.