The hydrodynamic behaviour of amylose tricarbanilate in dilute solution. V. The estimation of the unperturbed dimensions of amylose tricarbanilate from measurements carried out in good solvents

Abstract

AbstractTheories which separate short‐ and long‐range forces are applied to the experimental results for amylose tricarbanilate (ATC) in a good solvent (pyridine). The unperturbed dimensions obtained in this manner from light‐scattering, viscosity, and sedimentation measurements are compared with those obtained experimentally using a pyridine/water theta‐mixture. Satisfactory agreement is found when the FLORY‐OROFINO, or KRIGBAUM, treatment of the second virial coefficient is used, and also when the FIXMAN expression is applied to the measured coil dimensions. The apparent good agreement between the measured unperturbed dimensions and those obtained by means of the COWIE‐BYWATER treatment of the frictional coefficient is shown to be fallacious. Application of the STOCKMAYER‐FIXMAN treatment to viscosity measurements also leads to erroneous coil dimensions. Deviations from the hydrodynamic theories are shown to be due to the ATC macromolecule behaving as a partially free‐draining coil.Basic criteria to be satisfied in order to determine the unperturbed coil dimensions of polymers from measurements made in a good solvent are suggested.