How to measure effect of solvent and charged groups on polymer excluded volume and Kuhn length

Knowledge of solvent effect on polymer excluded volume and Kuhn length is a foundation of scaling analysis of solutions of charged and neutral polymers. Here we present an approach based on scaling relationship between solution correlation length ξ≈lg^ν/B and number of monomers per correlation blob g for polymers with monomer projection length l. Numerical coefficient B and exponent v are determined by solvent quality for the polymer backbone, chain Kuhn length and type and strength of monomer-monomer interactions at different length scales starting from solutions correlation length down to thermal blob length scales. Values of the B-parameters are obtained from a plateau of normalized specific viscosity η_sp(c)c^α/N as a function of monomer concentration c with degree of polymerization N. Exponent α=1/(1-3ν) describes concentration dependence of the number of monomers per correlation blob, g∼c^α. This approach allows one to extract excluded volume and Kuhn length as a function of fraction of charged monomers and salt concentration. We illustrate this approach on salt-free solutions of N-methyl-2-vinyl pyridinium chloride random copolymers in ethylene glycol and salt solutions of sodium carboxymethyl cellulose in water.