Adsorption of polymeric inclusion compounds on muscovite mica

alpha-Cyclodextrin, alpha-CD, which does not adsorb on mica, can be bound to this surface as a polymeric inclusion compound that is formed by threading many alpha-CD rings on a cationic polyelectrolyte, poly(decamethylenebipyridinium dibromide). The major driving force of the adsorption of the polymer and the polymeric inclusion compound is ion exchange with surface ions of mica. Somewhat less polymer is adsorbed when it is engaged in the inclusion complex than as pure polymer. The rates of adsorption for both the polymer alone and for the polymer in the inclusion compound depend strongly on the particular cation initially present at the mica surface (Li+ or K+); it is much more rapid with Li+. The equilibrium between complexed alpha-CD and uncomplexed alpha-CD, found in solution, is modified upon adsorption of the complex to favor the release of alpha-CD from the complex. However, the alpha-CD is only slowly released from the complex on the surface and, as a result, mica-bound complex can be isolated.