Synthesis of PPEGMEA-g-PMAA densely grafted double hydrophilic copolymer and its use as a template for the preparation of size-controlled superparamagnetic Fe3O4/polymer nano-composites

Abstract

A series of well-defined amphiphilic densely grafted copolymers, containing polyacrylate backbone, hydrophobic poly(methoxymethyl methacrylate) and hydrophilic poly(ethylene glycol) side chains, were synthesized by successive atom transfer radical polymerization. Poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer was firstly prepared via the grafting-through strategy. Next, poly[poly(ethylene glycol) methyl ether acrylate]-g-poly(methoxymethyl methacrylate) amphiphilic graft copolymers were synthesized via the grafting-from route. Poly(methoxymethyl methacrylate) side chains were connected to the polyacrylate backbone through stable C–C bonds instead of ester connections. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions were in the range 1.38–1.42. Poly(methoxymethyl methacrylate) side chains were selectively hydrolyzed under mild conditions without affecting the polyacrylate backbone to obtain the final product, poly[poly(ethylene glycol) methyl ether acrylate]-g-poly(methacrylic acid) densely grafted double hydrophilic copolymer. Finally, these double hydrophilic copolymers were used as templates to prepare superparamagnetic Fe₃O₄/polymer nano-composites with narrow size distributions via an in situco-precipitation process, which were characterized by FT-IR, TGA, DLS and X-ray diffraction in detail. The size of the nano-composites can be controlled in a certain range by adjusting the length of the poly(methacrylic acid) side chains and the weight ratio of copolymer to Fe₃O₄ nano-particle used.