Preparation and solution behaviour of graft copolymers with cationic groups in polyoxyethylene side chains

Novel, cationic graft copolymers with charged polyoxyethylene (PEO) side ch ains were prepared from the alternating copolymer poly(phthalimidoacrylate- co-styrene). Substitution of the good leaving phthalimido ester groups with alpha-trimethylammonioethyl-omega-aminopolyoxyethylene resulted in graft c opolymers with PEO side chains end-functionalized with quaternary ammonium groups. In a two-step synthetic procedure the same precursor polymer was mo dified with 3-dimethylaminopropylamine. Then the tertiary amine groups were quaternized with alpha-methoxy-omega-bromopolyoxyethylene or with alpha-tr imethylammonioethyl-omega-bromopolyoxye to yield graft copolymers with cati onic groups close to the backbone or bearing bifunctional side chains. The effect of ionic group location on the behaviour of the copolymers in a low- polarity and a polar solvent was studied by viscosity, GPC and static light scattering measurements. In a low-polarity solvent (tetrahydrofuran) the f actors determining the solution properties of the cationic graft copolymers are the intramolecular side chain and ion-pair attractions which shrink th e polymer chains. In a polar solvent (N,N-dimethylformamide) the behaviour of the graft copolymers with low degree of grafting is determined by the ba lance between the intramolecular side chain attraction and the electrostati c interactions of the dissociated ion-pairs. The ionic groups located at th e end of the side chains cause polyelectrolyte behaviour. (C) 2000 Elsevier Science Ltd. All rights reserved.