荧光探针法研究PMMA-g-PEG的胶束化行为

Micelle Formation of PMMA-g-PEG Copolymer by Fluorescence Probe Method

由聚乙二醇大分子单体(MA-PEG)与甲基丙烯酸甲酯(MMA)在二甲基甲酰胺(DMF)中进行共聚反应,生成了以PEG为支链,PMMA为主链的接枝共聚物(PMMA-g-PEG)。增加MA-PEG大分子单体的用量,可使PMMA-g-PEG的数均分子量略为增大,分子量分布保持在1.7左右。核磁共振测定表明PMMA-g-PEG的结构明确。进而以芘(Py)为荧光探针,测定了PMMA-g-PEG的临界胶束浓度(CMC),并跟踪了Py从H2O/DMF混合介质中向胶束的增容过程。表明PMMA-g-PEG的CMC较低时,介质中的水含量对Py的增容有较大的影响。透射电子显微镜观察发现,由PMMA-g-PEG自组装形成的聚合物胶束形态为球形,粒径在180nm左右,在水中具有稳定的形态结构。

Poly（methyl methacrylate） grafted poly（ethylene glycol） （PMMA-g-PEG） copolymers were prepared by radical copolymerization of methyl methacrylate （MMA） and poly（ethylene glycol） macromonomer （MA-PEG） with a methacryloyl end group in N,N-dimethylformamide （DMF） using 2,2＇-azobisisobutyronitrile as free radical initiator. Molecular weight distribution of the resulting PMMA-g-PEG copolymers was 1.7 based on the analysis of GPC. The structures of the PMMA-g-PEG copolymers were characterized by proton nuclear magnetic resonance （1H-NMR）. The results of NMR show that structure of the PMMA-g-PEG copolymer is clear. Critical micelle concentration （CMC） of the PMMA-g-PEG and the solubilization of pyrene from H2O/DMF mixed solvents to the micelles of PMMA-g-PEG copolymer were determined using pyrene as fluorescence probe. The results show that the PMMA-g-PEG has a low CMC and solubilization of pyerne depends upon water content in the mixed solvents. The shape of micelle with about 180 nm in diameter was observed by transmission electron microscopy （TEM）. The micelle had a stabilization form through self-assembly of PMMA-g-PEG copolymer.