Surface and subsurface film growth of titanium dioxide on polydimethylsiloxane by atomic layer deposition

Abstract

There has been increasing interest in polymers for biomaterial applications. Researchers have been trying to incorporate metal oxides or metals into polymers in order to attain significantly enhanced desirable properties of the resulting polymer material such as conductivity and antimicrobial activity. One promising technique for such materials is atomic layer deposition (ALD). By depositing a very thin film of metal or metal oxide, one can take advantage of these material properties without losing the unique bulk properties of the polymer; however, deposition of such a material on polymers becomes challenging in part due to the availability of both surface and subsurface film growth.In this study, atomic layer deposition (ALD) of TiO2 on polydimethylsiloxane (PDMS) is investigated at the early stages of nucleation and growth of TiO2 on both O2-plasma treated and non-plasma treated PDMS. X-ray absorption near edge structure, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy are used for material characterization. Results indicate that ALD-like surface growth of TiO2 takes place on plasma-treated PDMS; for non-plasma treated pristine PDMS, apparent favorable diffusion/infiltration of TiO2 into the subsurface of the polymer is obtained, without noticeable external surface deposition for at least the first 25 ALD cycles.