Redox-Responsive Polymer Brushes Grafted from Polystyrene Nanoparticles by Means of Surface Initiated Atom Transfer Radical Polymerization

Well-defined poly(2-(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA) brushes were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) on cross-linked polystyrene particles. The ATRP of FcMA monomer was reinvestigated leading to molar masses up to 130 kg mol(-1) with a good reaction control and high monomer conversion (91%). The SI-ATRP was done with different amounts of initiator in the PS particle shell leading to PFcMA surface conformations from mushroom like to dense brush like polymers, which could be confirmed by dynamic light scattering (DLS) experiments. Redox-responsive behavior of the PFcMA, shell was investigated by DLS and cyclic voltammetry (CV) measurements indicating a tremendous increase in the hydrodynamic volume of the ferrocene-containing shell. The transformation of PFcMA-grafted PS particles to magnetic iron oxides after thermal treatment could be investigated by SQUID magnetization measurements showing the typical hysteresis for ferromagnetic material.