SYNTHESIS AND MICELLIZATION BEHAVIOR OF ANIONIC FLUORINE-CONTAINING AMPHIPHILIC GRAFT COPOLYMERS

A novel series of anionic fluorine-containing amphiphilic graft copolymers P(HEMA-co-NaSS)-g-PEG were synthesized by graft copolymerization of poly (ethylene glycol) methyl ether methacrylate (MPEGMA) macromonomer, 2, 2, 3, 4, 4, 4-hexafluorobutyl methacrylate (HFMA) and sodium 4-vinylbenzenesulfonate (NaSS). The molecular structures of the amphiphilic graft copolymer were characterized by FTIR, H-1-NMR and F-19-NMR. The critical micelle concentration (CMC) of P(HEMA-co-NaSS)-g-PEG was measured by surface tension technique,indicating that the CMC increased gradually with increasing PEG branched chains and anionic contents in the copolymer. The average hydrodynamic diameter and size distribution of micelles were measured by dynamic light scattering (DLS). The measurement showed that the hydrodynamic diameter increased gradually with increasing the concentration of P(HFMA-co-NaSS)-g-PEG aqueous solution and the content of PEG branched chains in P(HFMA-co-NaSS)-g-PEG. The fluorescence spectrum showed that there was a significant interaction between P(HFMA-co-NaSS)-g-PEG micelles and bovine serum albumin (BSA). The fluorescence intensity of BSA decreased gradually in P(HFMA-co-NaSS)g-PEG/BSA aqueous solution with increasing the concentration of P(HFMA-NaSS)-g-PEG aqueous solution, HFMA segments and NaSS contents. Transmission electron microscopy (TEM) was used to investigate P(HFMA-co-NaSS) -g-PEG micelles and the aggregates of P(HFMA-co-NaSS)-g-PEG/BSA, the results showed that P(HFMA-co-NaSS)-g-PEG copolymers could self-assemble into core-shell structure micelles. Besides,with the decrease of HFMA contents in the copolymer,the morphology of P(HFMA-co-NaSS)-g-PEG micelles changed from a leaf-like structure to a spherical one. In particular, when BSA was added,the micelles changed from a tight core-shell structure into a loose vesicle-like structure, and the micelle size and size distribution also increased. TEM micrographs of P(HFMA-co-NaSS)-g-PEG/BSA displayed a visible adsorption phenomenon between P(HFMA-co-NaSS)-g-PEG micelles and BSA,and suggested that P(HFMA-co-NaSS)-g-PEG may have potential applications in loading proteins and other bioactive drugs.