Protein-Resistant Silicones:  Incorporation of Poly(ethylene oxide) via Siloxane Tethers

Silicones with enhanced protein resistance were prepared by introducing poly(ethylene oxide) (PEO) chains via siloxane tethers (a−c) of varying lengths. Three unique ambifunctional molecules (a−c) having the general formula α-(EtO)3Si(CH2)2-oligodimethylsiloxane n -block-poly(ethylene oxide)8-OCH3 (n = 0 (a), 4, (b), and 13 (c)) were prepared via regioselective Rh-catalyzed hydrosilylation. Nine films were subsequently produced by the H3PO4-catalyzed sol−gel cross-linking of a−c each with α,ω-bis(Si−OH)polydimethylsiloxane (P, M n = 3000 g/mol) in varying ratios (1:1, 1:2, and 2:3 molar ratio a, b, or c to P). Films prepared with a 2:3 molar ratio (a−c to P) contained the least amount of un-cross-linked materials, which may migrate to the film surface. For this set of films, surface hydrophilicity and protein resistance increased with siloxane tether length (a−c). These results indicate that PEO was more effectively mobilized to the surface if incorporated into silicones via longer siloxane tethers.