Selectively grafting polymer from the interior and/or exterior surfaces of bioreducible and temperature-responsive nanocapsules

A novel strategy is reported for selectively grafting polymer brushes from the interior and/or exterior surfaces of bioreducible and temperature-responsive nanocapsules. Poly(N-isopropylacrylamide-copoly(ethylene glycol) methacrylate) (P(NIPAM-co-PEGMA)) nanocapsules with hydroxyl groups at the interior surface, exterior surface or both surfaces were first prepared via seeded precipitation copolymerization of N-isopropylacrylamide and poly(ethylene glycol) methacrylate using N,N'-cystaminebisacrylamide (CBA) as the shell crosslinker, respectively. The location of hydroxyl groups at the interior surface or exterior surface or both surfaces was controlled via the addition time of poly(ethylene glycol) methacrylate (PEGMA). Then, Ce4+/mediated redox initiated polymerization was used to graft poly(2-(dimethylamino)ethyl acrylate) (PDMAEA) brushes from the surfaces of P(NIPAM-co-PEGMA) nanocapsules with the selectivity of the grafting position (the interior and/or exterior surfaces) being controlled via hydroxyl location. The resulting nanocapsules are temperature, pH and redox responsive.