Synthesis of poly-p-xylylene + CdS nanocomposites and studing of their surface structure

Abstract

Thin-film polymeric nanocomposites based on a poly-p-xylylene matrix (PPX) and nanoparticles of cadmium sulfide (CdS) have been obtained using solid-phase cryochemical synthesis on optical quartz substrates. The optimal conditions for the formation of PPX + CdS nanostructured polymeric films have been determined. The topography and surface characteristics of PPX + CdS nanocomposites have been studied by scanning atomic force microscopy (AFM). The characteristics of the morphological and structural changes of the film surfaces have been found at different CdS nanoparticle concentrations. These changes point to a reorganization of the PPX + CdS polymeric matrix. It is shown that at 2–10 vol % CdS concentration, the elements of the surface’s structural organization are polymeric nanofibers, parallel to the substrate plane, and a small number of nanoglobules, locally positioned directly on the nanofiber surfaces. Ordering of the surface structure accompanied by the formation of a periodic surface relief in the shape of nanoglobules was observed at a CdS concentration of 13.5 vol %. A mechanism of the formation of nanostructured PPX + CdS films is proposed. Based on the AFM experimental data, one can assume that during co-condensation of a p-xylylene monomer, CdS nanoparticles initiate radical polymerization of the PPX matrix, when the substrate is heated from 77 K to 300 K. The type of surface structure (fibrillar, fibrillar + globular and globular) depends on the nanoparticle concentration in the polymeric matrix.