ROTATIONAL BROWNIAN-MOVEMENT OF POLY(TETRAFLUOROETHYLENE) COLLOIDS AS STUDIED BY THE CONDUCTANCE STOPPED-FLOW TECHNIQUE

The rotational relaxation time and rotational diffusion coefficient (Dr) for ellipsoidal colloids of poly(tetrafluoroethylene) in aqueous suspension are determined conveniently and precisely by the conductance stopped-flow technique. The Dr values observed (13-21 s-1) are smaller than those calculated by Perrin's equation (80 s-1). The deviation can be explained by the significant contribution of the Debye-Hückel double-layer thickness (Debye screening length) in the absence of foreign salt. © 1990.