Self-diffusion in solutions of the polyblock polysulphone-polybutadiene copolymer

Abstract

Self-diffusion of macromolecules of the polyblock copolymer polysulphone-polybuttadiene in a mixture of common and selective solvents has been studied by NMR with a pulse magnetic field gradient. In the solutions an essentially non-exponential form of the diffusional attenuations of the magnetization was found indicating a wide distribution of the self-diffusion coefficients. Its form is well approximated by a logarithmically normal distribution function. The width of the distribution σ grows with increase in the fraction of selective solvent. The large σ values are explained by the existence of longlived clusters characteristics of gel-forming systems. The concentration dependences of the mean self-diffusion coefficient are discussed. These dependences for a high content of selective solvent have an anomalous form and are explained from the phase of the solutions.