Various molecular parameters characterizing solution properties of poly (N-isopropylmethacrylamide) (PNiPMAM) (in the range of moledular weight from 13.0 to 252 x 10 4) in water at 20°C were obtained by use of static and dynamic light scattering techniques. The molecular weight dependence of these parameters is expressed by the power law relation and compared with those for poly(N-isopropylacrylamide) (PNiPAM) in water. It was found that in aqueous solution PNiPMAM molecules take more expanded structures than PNiPAM molecules due to the presence of methyl group to the Cl-carbon.

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We report measurements of the effective viscosity and elasticity of a critical mixture of isobutyric acid and water in the process of phase separation under shear. The viscoelasticity of the sheared sample is a consequence of capillary forces associated with domain interfaces that produce linear domain growth in quiescent samples. We find agreement with a theory recently proposed by Doi and Ohta and obtain an estimate of the interfacial area per unit volume during spinodal decomposition.