MONOLAYERS ON DISORDERED SUBSTRATES - SELF-ASSEMBLY OF ALKYLTRICHLOROSILANES ON SURFACE-MODIFIED POLYETHYLENE AND POLY(DIMETHYLSILOXANE)

Self-assembled monolayers (SAMs) have been formed on disordered, polymeric substrates. On polyethylene (PE), preparation of the SAM entailed three steps: oxidation of the surface of the PE with an oxygen plasma; formation of a silicate layer anchored to the oxidized surface by reaction with SiCl4; formation of an alkylsiloxane surface layer by adsorption of alkyltrichlorosilanes from the vapor phase, and reaction with SiOH groups (and adsorbed water) on the surface of the silicate layer. On poly(dimethylsiloxane) (PDMS), plasma oxidation produced a surface silicate layer that could be used for subsequent adsorption of an alkylsiloxane layer without additional steps. The wettability of these SAMs is similar to that of comparable SAMs formed by adsorption onto better defined substrates (silicon wafers and gold). Reaction of SAMs on PE or PDMS bearing terminal vinyl groups with an aqueous pemanganate/periodate solution produced surfaces bearing carboxylic acid moieties.