Viscosities of Copolyphosphates in Salt-Free Aqueous Solutions and Theta Solvents I.

Abstract

ABSTRACT:The results of viscosity measurements on several samples of lithium-potassium copolyphosphates (Li: K ratio ranging from 9: 1 to 5: 5) in salt-free aqueous solutions and in theta solvents are reported. Molecular weights determined by end-group titration ranged from 4000-10000. In aqueous solutions the Fuoss equation parameter A was found to be nearly proportional to the square of molecular weights, indicating rod-like structures of the poly-ions at infinite dilution. The concentrations ofNaBr solutions acting as theta solvents at 35oC were determined for all cases and the viscosity data in 11-solvents were utilized in calculating unperturbed dimensions which were found to lie in the range 4.7 x 10-7 em to 7.4 x 10-7 em.KEY WORDS Lithium Potassium Copolyphosphates I Intrinsic Viscosity I Molecular Weight I Theta Solvent I Unperturbed Dimensions I Viscosity has played a major role in crystallizing our present views on polyelectrolyte shape dynamics. A review by Eisenberg and King 1 also emphasizes its importance in the study of ion-containing polymers. While a number of papers dealing with various aspects of the viscosity behaviour of solutions of longchain polyphosphates has appeared, none of them presents a detailed study on copolyphosphates, the counter-cation copolymers in which more than one kind of cations are attached to the polyphosphate backbone:

Atomistic Molecular Dynamic Simulation of Dilute Poly(acrylic acid) Solution: Effects of Simulation Size Sensitivity and Ionic Strength

“…The polymer chain expansion occurs as monitored by increasing the specific viscosity and radius of gyration and decreasing the sedimentation and translational diffusion coefficients. , To obtain information about the conformation of polyelectrolytes in aqueous solution and consequently to reveal the mechanism of its physical properties, a series of studies have been performed by different experimental techniques. The shrinkage and swelling phenomena of PAA chains were evaluated successfully by using a quartz crystal microbalance with dissipation monitoring (QCM-D) .…”