Polyelectrolytes adsorbed on the surface of cellulosic materials

The adsorption of two cationic polyelectrolytes onto carboxymethylated fibers of cellulosic pulp and rayon has been studied both by equilibrium measurements and in dynamic experiments with consecutive addition of the polyelectrolyte. For a low-molecular-mass polyelectrolyte, 3,6-ionene, the adsorption is rapid and the same result is obtained both in equilibrium and dynamic experiments except at low degrees of substitution. It is shown that there is almost a 1:1 stoichiometry between charges on the adsorbed polyelectrolyte and the total amount of carboxyl groups on the fibers which indicates that a cation exchange reaction is taking place. For a polyelectrolyte of a higher molecular mass, polydimethyldiallylammonium chloride (DMDAAC), the adsorption is lower and the resulting equilibrium adsorption is not stoichiometrically proportional to the charge on the fibers.