Preparation Of Star-PMMA Nanoparticles By Emulsion Atom Transfer Radical Polymerization

Because of their special structure and excellent performance, nanoparticles have attacted great concern of researchers, particularly in the pharmaceutical and biotech fields. However, in areas such as biomedical application often strictly requires the diameter of the particle size and monodispersity, and the traditional synthetical methods usually have some difficulties in the preparing monodisperse nano-sized particles., while more advanced technique were required.Since their inception, reversible addition-fragmentation chain transfer polymerization (RAFT), single electron transfer radical polymerization (SET-LRP) and the emulsion atom transfer radical polymerization (emulsion ATRP) also attracted great interest in polymer science, due to the usage of wide range of monomers, controlled/living charateristic and synthesis of a variety of special structure as well as star-polymers, comb polymers. Especially in recent years, as part of the RAFT agents have been industrialized and the discoveries of AGET ATRP and eATRP system have greatly promoted the development of these technologies. To a certain extent, these breakthroughs have brought controlled/living radical polymerization technique out of the laboratory, not just theorization.Dendritic-star polymer itself has a nano-structure, a clear body structure and the great amount of end functional groups. A number of dendrimer-star polymer also has a natural, small microcapsules and micro-cavity that can be used for embedding minimolecules such as the drug and targeting drugs, for the purpose of these reason,they has broad application prospects. However, the cost of dendrimers has not been resolved, in this case, with most properties of these dendrimers and less costly, small star molecules have become the best alternative substances.In this issue, star minimolecule acyl halides were synthesis by modification of pentaerythritol as ATRP initiator, and then the polymerization were implemented for the preparation of rare earth complexes fluorescent microspheres. Firstly, star-like PMMA nanoparticles with diameter smaller than 100nm and monodispersed were successfully prepared by emulsion atom transfer radical polymerization. Subsequently, the infrared, NMR, GPC, PCS, TEM and other equipments were used to characterize its structure, molecular weight and morphology characterization. Finally, the rare earth solvent with convenient concentration was added for coordination with the polymer for the studying of the fluorescent properties of rare earth complex by comparing with the linear polymer with the same amount of rare earth, the fluorescence properties of star polymer is stronger than the linear polymer with same dose of monomers.In order to get better fluorescent microspheres, and enhance its fluorescent properties, in the subsequent study, we attempt to introduce a better coordinated functional monomer maleic anhydride. Hydrolysis of maleic anhydride will produce double-keto structure, which can form more stable chelate structure with the rare earth; there will be a better fluorescence. By the introduction of the functional monomer, we have to look forward a new technique for the preparing of star maleic anhydride copolymer, which is the RAFT polymerization. The first step was to synthesis star-shaped RAFT agent, a more mature approach with which started by CS2 was conducted to synthesize the double disulfide ester RAFT agent, then star-RAFT agents were synthesiszed by two different pathways and the structures were characterized by NMR. The RAFT agent containing two-disulfide ester was successfully synthesized, but the results of the star-shaped RAFT agent were not clear. What's more, the ideal condition was still unknown for the purpose of time limitied.