Dynamic and static correlations in solutions of polymers in liquid and supercritical solvents: dynamic light scattering and small angle neutron scattering

Abstract

Using dynamic light scattering and small angle neutron scattering techniques we investigate the interrelation between the dynamic and static correlation lengths in liquid and supercritical polymer solutions in the poor solvent domain Θ ≥T≥Tc, where Θ is the theta temperature and Tc is the critical temperature of phase demixing. We observe the crossover between the hydrodynamic (T∼Θ) and critical non-diffusive (T∼Tc) regimes and demonstrate that the dynamic correlation length ξd* for polymers in liquid and supercritical polymer solvents is described by the universal function ξd*/ξd*(Θ)=F*(τ′) in terms of the de Genne’s scaling temperature variable τ′≡(T−Tc)/(Θ−Tc).