Study On The Synthesis, Characterization And Controlled Release Properties Of Amphiphilic Copolymers Using As Drug Carriers

N,N-dimethylaminoethyl methacrylate(DMAEMA) is a kind of environmental responsive compound which present sensitivity in response to both temperature and pH value.The polymers prepared from DMAEMA also exhibit sensitivity to external stimuli. As a kind of important functional material, β-cyclodextrin(β-CD) has been widely used in the fields such as chemical seperation and analysis, medicine industry and food industry. In this thesis, via Atom Transferred Radical Polymerization (ATRP), three copolymers were synthesized, including a comblike copolymer and two star-shaped compolymers using β-CD as their cores. The chain structures and their compositions were characterized using different advanced technologies including FTIR, ~1H NMR, GPC and DSC. And their lower critical solution temperature (LCST) was characterized by light scattering. In the end, we researched the copolymers' controlled-release behavior by choosing phenolphthalein as a model.The comblike amphiphilic copolymer has distinctive sensitivity in both temperature and pH. In different pH environment, the LCST can be controlled form 18℃ to 56℃. The copolymer has some characteristics of surfactant, and the CMC is around 2.0-2.5g/L. By DSC measurement, the copolymer presents a micro- phase separation character. The comblike copolymer exhibits satisfactory controlled- release property with a constant releasing behavior for 4 hours. While pH=2,the concentration of phenolphthalein is about 0.15g/L when the copolymers reach the constant releasing. However, while pH=8,the concentration of the drug decreased to 0.04g/L.The star-shaped block copolymers with β-CD as a core have higher LCSTs than the comblike copolymers. The LCSTs can be influenced by the molecular weight (M_w) of the arm and the number of the arms. With the increase of the M_w and the number of the arms, the LCST decreased from 62℃ to 54℃. Accordingly, their pH sensitivity was not so distinctive than the comblike copolymers. Because of the unique structures, the star-shaped block copolymers did not exhibit a clear amphiphilic character. In the controlled- release study, the copolymers needed more time to reach a constantreleasing. The constant concentration of the drug is about 0.09g/L.Another star-shaped copolymer was synthesized by ATRP, and its branch chain was composed by comblike copolymers. Their LCSTs were influenced by the heating rate, the concentration of solution, the molecular structure and pH. The study suggests that the copolymer exhibits different releasing behavior under different temperature. At 39°C, the releasing rate can be slightly accelerated. And with more lower drug loading, the copolymer can reach the constant release in more few hours.The sameness and difference of the release property of the three copolymers was compared in the end of this thesis. In the beginning of the release process, the comb-like copolymers have higher releasing rate than the other two star-shaped copolymers. So their releasing patterns incline to be "outburst", which will lead to the fluctuation of the concentration of phenolphthalein. Though the star-shaped copolymer can't reach the constant releasing in short time, it can easily resist the fluctuation of the concentration of phenolphthalein in aqueous solution. Hence the star-shaped copolymers (with blocked or grafted arms) have a more satisfactory controlled-release property on phenolphthalein.