Mechanism of poly(methyl methacrylate) film formation by pulsed laser deposition

Abstract

The formation of poly(methyl methacrylate) films during pulsed laser deposition was studied by deposition at different substrate temperatures and by using targets with defined molecular mass and tacticity. At room temperature, the films (deposited from high-molecular weight polymer targets) mainly consist of macromolecules with average molecular masses of about 8000 g/mol. Up to substrate temperatures of 100 degrees C, this average mass remains constant, suggesting the transport of larger polymeric fragments from the target to the substrate surface. This hypothesis is also confirmed by experiments using target material of lower molecular weight and of defined tacticity. At temperatures above 100 degrees C and thus at conditions of enhanced mobility, the substrate molecular weight increases with temperature. The experiments indicate that the films are formed by deposition and reaction of macromolecular species. Radical polymerization of monomers described in the literature as a dominating film formation process plays no significant role. (c) 2006 American Institute of Physics.