Conductance stopped-flow study of the association reaction of colloidal spheres with poly(vinylpyrrolidone)

Abstract

The equilibrium and kinetic parameters of the association reaction of colloidal spheres with poly(vinylpyrrolidone)(PVP) have been estimated, for the first time, using the conductance stopped-flow (CSF) technique. Colloidal silica spheres (13.5 and 25 nm in diameter) and polystyrene latex spheres (85, 91, 109 and 455 nm in diameter) were used. Relaxation traces of the CSF measurements were obtained by mixing the spheres with PVP solutions. The binary association rate constants (k_f= 10³–10⁶ dm³ mol^–1 s^–1) are much smaller than those of a diffusion-controlled reaction. Both k_f and the equilibrium association constant decrease as the size of the spheres increases.