Functional polymers in the generation of colloidal dispersions of amorphous selenium

Abstract

Stable colloidal dispersions of red, amorphous selenium have been prepared by the reduction of selenious acid in dilute aqueous solutions of hydrazonium polyacrylate. The initially formed particles average 1000-1200 A, in diameter. These particles can be grown by adding hydrazine and selenious acid in a cyclical fashion. Reduction of selenious acid in a control system in which hydrazonium propionate was substituted for the hydrazonium polyacrylate yielded a flocculent precipitate of amorphous selenium. The formation of the stable colloidal dispersion in the presence of the functional polymer can be understood in terms of a locus control formalism, which views the discrete polymer molecules as loci (submicroscopic reaction vessels) to which the reaction is restricted. Stable colloidal dispersions are then obtained because stabilization occurs in the same volume element in which the particle is nucleated. Hydrazonium salts of acrylic acid copolymers and other polyacids can also be utilized in the preparation of stable colloidal selenium dispersions.