Methods of forming and using a polymer dispersion are described herein. The polymer dispersion includes a plurality of polythioaminal microparticles in a fluid medium that does not dissolve the plurality of polythioaminal microparticles. The fluid medium may be aqueous, for example water. The polymer dispersion may be applied to a substrate, and the fluid medium removed, to form an article substantially made of a polymerized polythioaminal mass. The dispersion, and any article made from the dispersion, may include pigments and active ingredients, such as biocides.