Surface laser light scattering studies of the air/poly(N-vinyl-2-pyrrolidone)-water solution interface

Abstract

An experimental study of poly(N-vinyl-2-pyrrolidone) (PVP) in water solution has been carried out by using the surface laser light scattering (SLLS) technique. The concentration dependence data of the peak frequency and linewidth are obtained from the SLLS spectra of the PVP/water solutions with two PVP molecular weights over a wide concentration range varying from the dilute to semidilute regime. The equilibrium surface tension of the solution is also measured as a function of polymer concentration and molecular weight. In the dilute solution, the peak frequency and surface tension show only a small decrease with increasing concentration. However, in the semidilute concentration regime, the surface tension and the frequency shift decrease rapidly with increasing concentration, accompanied by the dramatic increase in the spectral linewidth. The surface tension, SLLS spectral peak frequency and linewidth show an important molecular weight dependence. Over the entire concentration range investigated, the SLLS data of the PVP/water solutions do not show evidence of the capillary to Rayleigh wave evolution.