Improved relationships for diffusion and sedimentation constants and for viscosity and streaming birefringence of solutions of polymers

Abstract

For the description of the practical properties of a large number of linear polymer molecules as well as for the discussion of the various mean parameters of the individual chain molecule, the model usually employed to represent the molecule consists of N m straight line chain elements of length A m statistically joined to each other (straight element model). For the construction of large‐scale wire models of polymer molecules to be used in model experiments on the hydrodynamic behavior of chain molecules, a somewhat different model (circular segment model) was employed in previous papers. In these papers the relationships connecting the parameters which characterize these two models respectively have been determined on the basis of certain assumptions. These assumptions, as has recently been shown, were however partly in error and certain corrections have now to be applied to the numerical constants which appear in previously published formulas for the diffusion and sedimentation constants and for the intrinsic viscosity and streaming birefringence. The formulas, resulting after these corrections have been incorporated, are compiled in the present paper and the effect of these corrections on the interpretation of both new and old experimental results is discussed. It is found that agreement between theory and experiment is improved by the use of the corrected expressions and that in particular certain discrepancies which had previously existed between the lengths A m of the statistical chain element as calculated from sedimentation and diffusion experiments, on the one hand, and viscosity determinations on the other, disappear after these corrections are applied (see Table I).

The change of DNA structure by specific binding of the cAMP receptor protein from rotation diffusion and dichroism measurements.

“…In the case of DNA helices the rotation time r is mainly determined by the helix length. The chain length dependence of T, observed in the range up to -300 bp, can be described with satisfactory accuracy by a weakly bending rod model (Kuhn et al, 1953;Hearst, 1963;Elias and Eden, 1981;Diekmann et al, 1982b). According to this model in the form developed by Hearst (1963) where k is the Boltzmann constant, Tis absolute temperature, -1 is solvent viscosity, L is contour length of the rod, b is distance between frictional elements, a is Stokes diameter of each element and 1/X is statistical length corresponding to twice the persistence length.…”

The hydrodynamic behaviour of amylose tricarbanilate in dilute solution. IV. A comparison of experimental and calculated coil dimensions for amylose tricarbanilate in a pyridine/water theta‐solvent

“…)1/2 calculated using Eqs. (5) and (6) in conjunction with Eq. (9) are shown later in Tables 4 and 5.…”

Theories Of Streaming Double Refraction

“…In discussing their theory for the elastic dumbbell model W. Kuhn and H. Kuhn (73,74,75) regard equations 143 and 148, with the value of Xm given by equation 151, as being essentially true for the three-dimensional case, and when allowance is made for the lateral dimensions of the coil; they consider only small changes in the numerical factors are involved. The final expressions given (79,80) are, with the usual notation, M _043_ Na Z Am2b (-1.6 + 2.3 log (Am/dh) + Am«2) 102 M" sm From equation 154, the quantity T 0 C-»0 which henceforth will be written as T tan (xG)0, is given by…”