Synthesis of PEO-based block copolymers bearing cyclic hydrazide or carboxylic acid moieties and their applications as stabilizers for Fe ₃O₄ nanoparticles

In this paper, a useful synthetic method for poly(ethylene oxide)-based block copolymers and their applications for preparation of iron oxide nanoparticles were introduced. Poly(ethylene oxide-b-N-phenylmaleimide) was first synthesized by anionic block copolymerization of ethylene oxide and N-phenylmaleimide (N-PMI) using mixed alkali metal alkoxides via the sequential monomer addition technique in a mixture of benzene dimethylsulfoxide (DMSO)/tetrahydrofuran (THF) (30/5/6 ∼20, v/v/v) at room temperature. Reductive deimidation of the resulting block copolymers under different reaction conditions using hydrazine monohydrate led to the formation of the corresponding water-soluble poly(ethylene oxide-b-maleic hydrazide) under acidic conditions and poly(ethylene oxideb-maleic acid) under basic conditions. Both were found to be very efficient stabilizers to prepare superparamagnetic iron oxide nanoparticles.