Amphiphilic silicones prepared from branched PEO-silanes with siloxane tethers

Amphiphilic silicones were prepared by the covalent incorporation of branched polyethylene oxide (PEO) via a siloxane tether. This was achieved by using six novel branched PEO-silanes with varying siloxane tether lengths and PEO molecular weight (M_n). Each PEO-silane was crosslinked via acid-catalyzed sol–gel condensation with α,ω-bis(Si-OH)polydimethylsiloxane (PDMS) (M_n = 3000 g/mol) to yield six amphiphilic silicone films. Film surface hydrophilicity increased with siloxane tether length, particularly after exposure to an aqueous environment, indicating that the PEO segments were more readily driven to the surface. This effect was more pronounced for films prepared with PEO-silanes containing lower M_n PEO segments. AFM was used to study surface reconstruction of films upon exposure to an aqueous environment. Adsorption of bovine serum albumin (BSA) and human fibrinogen (HF) proteins decreased with siloxane tether length, particularly after first exposing films to an aqueous environment. For a given siloxane tether length, relatively less BSA adsorbed onto films prepared with PEO-silanes with lower M_n PEO segments whereas less HF adsorbed onto films prepared with PEO-silanes with higher M_n PEO segments.