pH and thermo-responsive graft copolymers are reported where thermo-responsive poly(N-isopropylacrylamide) [poly(NIPAAm), poly A], poly(N-isopropylacrylamide-co-2-(diethylamino) ethyl methacrylate) [poly(NIPAAm-co-DEA), poly B], and poly(N-isopropylacrylamide-co-methacrylic acid) [poly(NIPAAm-co-MAA), poly C] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic-imine bond. All the prepared graft copolymers for PEG-g-poly(NIPAAm) [P-N1], PEG-g-poly(NIPAAm-co-DEA) [P-N2], and PEG-g-poly(NIPAAm-co-MAA) [P-N3] were characterized by H-1-NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013