Synthesis And Characterization Of PEG Polymer Brushes Functionized With Triazole Via Cyclopolymerization

Polymer brushes, which a densely packed layer of tethered polymers anchored on the surface utilizing the end-functionality of the polymer chain, are named due to the shape like a brush. Recently, end-reactive poly(ethylene glycol)s (PEG) have become more and more important in a variety of fields such as biology, biomedical science, and surface chemistry, due to their unique properties such as solubility and flexibility of the chains and basicity of the ether oxygens in the main chain. The method of construction of polymer brushes with PEG chains is that a densely packed layer of tethered polymers anchored on the surface utilizing the end-functionality of the polymer chain.In this paper, we design and synthesize the PEG polymer brushes with the11-member ring as structure backbones, and study the structure and property of the polymer brush. The main results are summarized as follows:(1) Design and synthesis of the macromolecular monomer. The1,2,3-triazole-tethered diacrylate monomers with different PEG lengths are synthesized via the so-called "Click Chemistry" and the esterification. NMR analysis indicate the structure of monomer and precursor, the results demonstrate the monomers are the diacrylate monomers with1,2,3-triazole and PEG side chains.(2) Synthesis of PEG polymer brushes. PEG polymer brushes are synthesized directly via RAFT cyclopolymerization of diacrylate monomers bearing PEG functional groups through the formation of11-member rings. The studies, namely polymerization of monomers with different concentration and the kinetics of polymerization, show the diacrylate monomers have the strong tendency to cyclopolymerization rather than crosslinking. NMR analysis, GPC profiles and the datum of the kinetics prove the high efficiency of cyclopolymerization without side reactions.(3) The fluorescence of PEG polymer brushes. The aqueous solutions of the obtained PEG polymer brushes are fluorescent under UV excitation. The fluorescence depends dramatically on the concentration of brush-like polymers due to the aggregation of cyclopolymer in water. We study the interaction between PEG polymer brushes and DNA by the change of fluorescence intensity, and the result is that the fluorescence of PEG polymer brushes could be quenched by the addition of DNA.