Order and disorder in Polymer Systems : Structure and Dynamics

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1.Dkynamic and static properties of linear polymers in the solution and bulk states.(1)Dynamic properties Dynamics of flexible polymers in concentrated systems was studied by dielectric dispersion method, which revealed some problems in the reptation model theories. For polymeric materials, mechanical responses to large deformation and local molecular motion near the glass temperature were investigated by the following methods : (a)the use of bimodal-distribution polymer samples, (b)the measurement of differential dynamic mudulus, (c)the study of the uniaxial and biaxial extension deformations, and(d)the simultaneous measurements of dynamic viscoelasticity and birefringence. The polymer motion near the glass temperature classified into two types, each of which was molecularly interpreted.(2)Static properties Thermodynamic and spatial properties of stiff-chain polymer systems were explained by molecular theories different from theories of flexible polymers. Anisotropic interaction between polymer chains in polymer blend systems was studied by infrared dichroism, and it was shown to be important for the miscibility of the blends. The screening of the intramolecular excluded volume effect was studied by computer simulation.2.Polymeric systems with current interestsOn the basis of the above results for homogeneous systems of linear polymers, the research was extended to the following systems with current interests : (a)branched polymers [star-shaped and tree-like polymers, poly(macromonomer)s], (b)chemically and physically cross-linked polymer gels, (c)macro-and micro-phase-separated polymer systems, and(d)polymers in interface. New computer simulation techniques were applied to the systems(a)and (c), new theories were developed for the systems(a)-(d), and new experimental techniques(e.g., neutron scattering and refractivity measurements)were used to study the systems(b)and(d).