Friction coefficients in self‐diffusion, velocity sedimentation, and mutual diffusion for poly(ethylene oxide) in aqueous solution

The concentration dependences of the friction coefficient(s) for poly(ethylene oxide) have been determined on well‐defined fractions in dilute aqueous solution. Three independent techniques have been used: FT‐pulsed field gradient NMR (self‐diffusion), photon correlation spectrosccpy (mutual diffusion), and velocity sedimentation, in the concentration range 1‐25 kg m −3 . The results establish that, at a given concentration, the friction coefficient in self‐diffusion is appreciably smaller than that operating in mutual diffusion and sedimentation; the friction coefficient in the latter processes are identical within experimental error.