Rotational relaxation time and conformation of salt-free sodium poly(styrenesulphonate) as studied by the conductance stopped-flow technique

Abstract

The rotational relaxation time (τ_f) of sodium poly(styrenesulphonate)(NaPSS) in aqueous media has been determined using the conductance stopped-flow technique. The effective length of a single chain may be evaluated from τ_f. The conformation of the macroion chain is inferred to be highly stretched at dilute concentrations lower than 10^–3 mol dm^–3, and shrinkage of the chain occurs with increasing polymer concentration and/or with added salt. The persistence length evaluated from τ_f decreases sharply with polymer concentration and slightly with increasing degree of polymerization. The Debye screening length is discussed in relation to the solution properties of salt-free NaPSS.