Degradable\nand Chain Extendable Segmented Hyperbranched\nCopolymers by Wavelength-Selective Photoiniferter Polymerization Using\na Trithiocarbonate-Derived Dimethacrylate

In\nthis study, segmented hyperbranched copolymers with degradable\nand chain extendable cross-linker branch points were synthesized via\ngreen light-activated photoiniferter copolymerization of poly(ethylene\nglycol) methyl ether methacrylate (PEGMA) and a trithiocarbonate-derived\ndimethacrylate. A series of segmented hyperbranched copolymers with\ndifferent degrees of branching were synthesized by changing the feed\nratio of PEGMA to cross-linker to chain transfer agent. The segmented\nhyperbranched copolymers could be degraded into linear polymer chains\nby removing the trithocarbonate groups, which provides fundamental\ninsights into the growth of primary chains during photoiniferter copolymerization.\nSwitching to blue light irradiation allowed for the chain extension\nof poly(<i>N</i>,<i>N</i>-dimethylacrylamide)\n(PDMA) both at the branch points and at the chain ends. Finally, the\nformed segmented hyperbranched copolymers were explored as macromolecular\nchain transfer agents to prepare segmented hyperbranched block copolymer\nnanoparticles via polymerization-induced self-assembly. This study\nnot only leads to new examples of degradable and chain extendable\nsegmented hyperbranched polymers but also provides important insights\ninto the formation of branched polymers via copolymerization of multivinyl\nmonomers.