Jacob Riseman

A theory of the intrinsic viscosities and translational diffusion constants of flexible macromolecules is developed on the basis of the random coil model with hindered internal rotation. Proper account is taken of the hydrodynamic interaction of the monomer units of the molecule and of inhibited flow through the chain. The theory leads to results qualitatively similar to those obtained by Debye on the basis of a molecular model consisting of a sphere containing a uniform distribution of resisting points. However, significant quantitative differences between the two theories are found.

First Page

A theory of the intrinsic viscosities, translational and rotatory diffusion constants of rod-like macromolecules in solution is developed on the basis of a rigid-chain model made up of monomeric elements separated by rigid bonds. The general methods of previous papers are used to take proper account of the hydrodynamic interactions of the monomeric units of the molecule. The theory developed leads to results showing qualitatively, marked similarity to that obtained for cylindrical and ellipsoidal particles. The intrinsic viscosities, translatory and rotatory diffusion constants are shown, as in the case of flexible macromolecules, to be related through a pair of parameters. A method for obtaining the molecular weight of rod-like macromolecules is proposed, based on the combination of intrinsic viscosity and rotatory diffusion constant measurements.

The theory of the concentration dependence of the viscosities of solutions is developed for the dumbbell, rigid rod, and flexible chain macromolecules. Both the intramolecular hydrodynamic interactions between the monomer units of the same molecule and the intermolecular interactions between monomer units of different molecules are considered. The methods of Riseman and Kirkwood are applied throughout. The numerical result of the calculation for the dumbbell shaped molecule is compared with that obtained by Simha.

Abstract During recent years attempts have been made to formulate a viscosity‐concentration relationship. The method of Huggins, in introducing a factor k′ as a hydrodynamic correction factor is examined, and in particular the attempts to draw conclusions relating k′ to the thermodynamic properties of the solution. An explanation is offered to correlate the experimental viscosity‐concentration relationship and the change of solvent. A possible method for the actual calculation of concentration effects has been applied to the case of a suspension of spherical particles, for which, as a first approximation, a value of 10.6 for the coefficient of the c 2 term has been obtained.