THE SPECIFIC VISCOSITY OF PARTIALLY HYDROLYZED POLYACRYLAMIDE SOLUTIONS - EFFECTS OF DEGREE OF HYDROLYSIS, MOLECULAR-WEIGHT, SOLVENT QUALITY AND TEMPERATURE

The dependences of the specific viscosity of several polyelectrolytes on poly electrolyte concentration, salt concentration or solution ioni c strength, solution pH value, solvent quality, and solution temperatu re were systematically investigated. We found that the specific viscos ity obeys a more general relation: eta(sp) = Ac-p(2)/(c(p) + 2C(s))(3/ 2) + B, where eta(sp) is the polyelectrolyte specific viscosity, c(p) and c(s) are polymer and salt concentrations, respectively. The prefac tor A depends critically on chain size, solvent quality, and temperatu re in qualitative agreement with the theory proposed by Rabin et al. T he intercept B is nonzero or less than zero in polyelectrolyte solutio ns with low ionic strength. When a sufficient amount of salt has been added, B is reduced to zero and we recover the Rabin et al.'s relation . The physical interpretation for the intercept B is that it represent s the inverse of the strength of electrostatic interaction between a p olyion and counterions, in quantitative agreement with the well-known emperical Fuoss's relation. Furthermore, the existence of nonzero B al lows us to calculate the condition for the maximum in the reduced visc osity-polymer concentration curve in a polyelectrolyte solution system without salt. (C) 1998 John Wiley & Sons, Inc.