Synthesis, self‐assembly and redox‐responsive properties of well‐defined hydroxypropylcellulose‐graft‐poly(2‐acryloyloxyethyl ferrocenecarboxylate) copolymers

Well-defined amphiphilic graft copolymers, hydroxypropylcellulose-graft-poly(2-acryloyloxyethyl ferrocenecarboxylate) (HPC-g-PAEFC), were synthesized via atom transfer radical polymerization. The graft copolymers contain hydrophilic thermo-responsive HPC backbones and hydrophobic redox-sensitive PAEFC side chains and can self-assemble into spherical micelles in aqueous solution, with a hydrodynamic radius in the range 70-130 nm depending on length of the graft chains. The thermo-responsive properties of the HPC-g-PAEFC copolymers in aqueous solution are gradually destroyed with increasing length of PAEFC side chains. The redox-responsive behaviors of the graft copolymers were investigated with H2O2 and sodium ascorbate as oxidant and reductant, respectively, indicating an incompletely reversible redox-triggered size transition. And the reversibility of the redox process becomes weaker gradually as the side chains are more difficult to be oxidized with an increase of the graft chains, which is evidenced from cyclic voltammetry measurements. The resultant HPC-g-PAEFC graft copolymers with the unique properties of ferrocene and cellulose provide prerequisites for amperometric biosensors and redox-responsive drug delivery carriers. (c) 2015 Society of Chemical Industry