Synthesis And Characterization Of Novel Block And Graft Copolymers For Pickering Emulsion

Pickering emulsion is a heterogeneous dispersion system stabilized by solid particles adsorbed at the interface between water and oil.Pickering emulsions possess many advantages over traditional surfactant stabilized emulsions,such as their high stability,low toxicity and adjustable droplet size.These merits endowed it wide applications in many fields including material synthesis,oil industry,food industry,and interface reaction,etc.Most of studies on Pickering emulsions have been centered on the water-oil system,including oil-in-water and water-in-oil.However,the existence of water is unfavorable in some cases in which Pickering emulsions were used as microreactor for water-sensitive reactions,or as the carriers for the encapsulation of drugs that were liable to hydrolysis.As a result,the study on non-aqueous Pickering emulsion is also very significant.Whatever Pickering emusion or non-aqueous Pickering emulsion,the crucial factor for the formation of the stable emulsion was the particulate emulsifiers with high interfacial activities.Therefore,it is very significant to explore nanoparticles with high interfacial activities in the field of emulsion.Compared with the solid particles,the interfacial activities of polymeric particles could be flexibly regulated.Herein,the main work was centered on the synthesis of polymeric nanoparticles with high interfacial activities.（1）Synthesis of single-chain polymer nanoparticles（SCPNs）for the formation of Pickering emulsion and non-aqueous Pickering emulsion.SCPNs were synthesized through the intramolecular cross-linking of the reactive PDMAEMA block of PDMAEMA-b-G₄linear-dendritic diblock copolymers.PDMAEMA-b-G₄exhibited a linear PDMAEMA block and a dendritic fourth-generation aliphatic polyester block,which was synthesized through the combination of click reaction and RAFT polymerization.The intramolecular cross-linking of the reactive PDMAEMA block of PDMAEMA-b-G₄was conducted in DMF at a concentration of 1 mg/m L using1,4-diiodobutane as the cross-linkers.The successive cross-linking reaction was confirmed by ¹H NMR and GPC as well as TEM observation.The resultant SCPNs exhibited high interfacial activities and could act as Pickering emulsifiers for the formation of different types of Pickering emulsions including water-in-oil and oil-in-oil as well as ionic liquid-in-oil systems.（2）Synthesis of novel amphiphilic heterograft copolymers for the formation of Pickering emulsion and non-aqueous Pickering emulsion.A novel kind of multiphiphilic heterograft copolymer exhibiting polyurethane（PU）mainchain and two different side chains,namely poly（N,N-dimethylacrylamide）（PDMA）and poly（methyl methacrylate）（PMMA）,was synthesized by the combination of polyaddition reaction and the living radical polymerization reaction.For the synthesized amphiphilic PU-g-PDMA/PMMA heterograft copolymers,PDMA side chain and PMMA side chain were quantitatively grafted on the same graft site.Amphiphilic PU-g-PDMA/PMMA heterograft copolymers could self-assemble into spherical micelles in the selective solvent of benzene.Using the spherical micelles as particulate emulsifiers,different types of Pickering emulsions including water-in-oil and oil-in-oil could be formed.The structure of PU-g-PDMA/PMMA was characterized,and the emulsification performances of micelle were studied.