synopsisOf the 30 monomers and monomer combinations investigated, 11 were polymerized into essentially all powder, 17 into predominantly a film, and two could not be polymerized in an electrodeless rf plasma-initiated gas phase polymerization. Efficient powder formation was mainly determined by the type of the monomer, the monomer partial pressure, the type of inert gas used, and the design of the polymerization chamber. The powders examined consisted of spherical particles of submicron size and were almost completely or partially soluble; and in the case of polystyrene, the powders possesses a very narrow particle-size distribution. In all cases, the soluble material was of a very low molecular weight. The best conversion to powder achieved was 18%.