Dynamics of Chains in Dilute Solutions

When a large rigid sphere is suspended in a solvent, its dynamical properties, such as the velocity autocorrelation function, mean square displacement, dynamic structure factor, etc., are well known, and form the basis of suspension theory from Einstein onwards. 

in the intermediate regime, the time explored is longer than the characteristic time for the various trans-gauche conformational transitions (which in turn depends on the chemical nature of the monomers), the dynamical behavior of the polymer chain in this regime is independent of the chemistry of the chain. We call this independence of the local details as the global features of the chain dynamics. 

We need to know the characteristic time beyond which we will cease to observe the global chain dynamics but only the center of mass motion. In answering such a question we need the relaxation time for a polymer chain which has been disturbed from its equilibrium configuration, and the mean square displacement of a labeled monomer as a function of time. 

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The Rouse model has been extended to deal with the dynamics of chains in dilute solution [18], In solution a moving bead perturbs the solvent flow around another bead, leading to effective, so-called hydrodynamic, interactions. The Zimm model generalizes the Rouse model by taking hydrodynamic interactions into account. 

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