Behaviour of poly(N,N-Dimethylacrylamide-co-2-methoxyethylacrylate) in non-aqueous solution and LCST behaviour in water

N,N-Dimethylacrylamide (DMA) has been copolymerized with 2-methoxyethylacrylate (MOEA) to yield four copolymers of different composition, which were fractionated isothermally on the basis of molecular mass. PMOEA homopolymer was prepared and also fractionated. Cloud point curves for five fractions of each copolymer in water were determined over a wide interval of concentration, solubility being found to decrease on heating. Analysis of data by the Shultz-Flory procedure afforded the lower critical solution (theta) temperature and entropy of dilution parameter psi(1). The copolymer of highest content of MOEA displayed anomalous behaviour, viz. the critical consulute temperature was independent of molecular mass and psi(1) was infinite. To explain this effect, clustering of hydrophobic moieties in water is proposed and is supported by values of hydrodynamic diameter measured by dynamic light scattering. Results are also presented of viscometric measurements on solutions of PMOEA and copolymers in toluene at 298 K. (C) 1997 Elsevier Science Ltd.