Polystyrene segmental diffusion

D. A. Waldow, M. D. Ediger, Y. Yamaguchi, Y. Matsushita, and I. Noda. Viscosity dependence of the local segmental diffusion of anthracene-labeled polystyrene in dilute solution. Macromolecules, 24 (1991), 3147-3153. 

Let s use the obtained numerical values of the characteristic times of the segmental movement for the estimation of dynamical properties of the polystyrene chains that is their characteristic time of the translational movement t and coefficient of diffusion D into solutions and melt. Accordingly to Ref [25], the values t and D are determined by the expressions ... 

What is explained above concerning the diffusion of the Rouse segment in polystyrene melts can similarly be applied to the molecular diffusion Dg in OTP i.e. 

Molecular motion in polymer solutions can have significant effects on the physical properties of the systems formed from these solutions. For example, the rates of drying polymer films can determine the film properties. We have shown that the drying of a polystyrene film from toluene solutions could be predicted with the knowledge of thermodynamic parameters, plus solvent diffusion data.(i) The ability of polymers to respond to changes in conditions is determined by die ability of the polymer and/or its segments to reorient. Solvent diffusion is also correlated to the segmental motions of the polymer chains.(2) The reason for this correlation appears to be that both molecules are coupled to the same fractional free volume. 

Proton spin-temperature equilibration between the hard- and soft-segment-rich domains of the polyurethane elastomer on the order of 10-100 ms might be considered fast relative to a macroscopically phase-separated blend [26] or copolymer, but slow relative to a strongly interacting mixture [25]. This is reasonable for a microphase-separated material whose solid state morphology has been the subject of considerable theoretical and experimental research. Under fortuitous circumstances, intimate (near-neighbor) contact between dissimilar molecules in a mixture can be studied via direct measurement of proton spin diffusion in a two-dimensional application of the 1H-CRAM PS experiment (Combined Rotation And Multiple Pulse Spectroscopy). Belfiore et al. [17,25,31] have detected intermolecular dipolar communication in a hydrogen-bonded cocrystallized solid solution of poly(ethylene oxide) and resorcinol on the f00-/xs time scale, whereas Ernst and coworkers [26] report the absence of proton spin diffusion on the 100-ms time scale for an immiscible blend of polystyrene and poly(vinyl methyl ether), cast from chloroform. 

The SRLS mechanism has been invoked to explain the segmental rotational dynamics of spin-labeled polystyrene in toluene solution. This study provides an example of a system in which the dynamic cage is defined by constrained diffusion of the spin label attached to a polymer. The SRLS model is appropriate to analyze these spectra, since the local ordering environment is coupled to the global tumbling modes of the polymer. Moreover, the high (250-GHz) frequency ESR spectra of this... 

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