Synthesis and self-assembly of a hydrophilic, thermo-responsive poly(ethylene oxide) monomethyl ether-block-poly(acrylic acid)-block-poly(N-isopropylacrylamide) copolymer to form micelles for drug delivery

A hydrophilic, thermo-responsive triblock copolymer poly(ethylene oxide) monomethyl ether-block-poly(acrylic acid)-block-poly(N-isopropylacrylamide) (MPEO-b-PAA-b-PNIPAM) was synthesized by sequential atom transfer radical polymerization and hydrolysis. These polymers were characterized in detail by 1H NMR, FT-IR and gel permeation chromatography. In aqueous solution, MPEO-b-PAA-b-PNIPAM can self-assemble into core-shell-corona micelles above a LCST of the PNIPAM block. Condensation reactions easily cross-link the PAA shells, which enhances micellar stability. Doxorubicin (DOX), a model drug, was loaded into the core of the polymeric micelles and followed a pattern of thermo-sensitive drug release in vitro in cumulative release studies.