Formation of self-assembled monolayers by chemisorption of derivatives of oligo(ethylene glycol) of structure HS(CH2)11(OCH2CH2)mOH on gold

Article abstract of DOI:10.1021/ja00001a002

This paper describes the preparation of oligo(ethylene glycol)-terminated alkanethiols having structure HS-(CH₂)₁₁(OCH₂CH₂)_mOH (m = 3-7) and their use in the formation of self-assembled monolayers (SAMs) on gold. A combination of experimental evidence derived from X-ray photoelectron spectroscopy (XPS), measurement of contact angles, and ellipsometry implies substantial disorder in the oligo(ethylene glycol)-containing segment. The order in the -(CH₂)₁₁- group is not denned by the available evidence. The SAMs are moderately hydrophilic: θ_a(H₂O) = 34-38°; θ_r(H₂O) = 22-25°. A study of monolayers containing mixtures of HS(CH₂)₁₁CH₃ and HS(CH₂)₁₁(OCH₂CH₂)₆OH suggests that the oligo(ethylene glycol) moieties are effective at preventing underlying methylene groups from influencing wetting by water. A limited study demonstrates that these oligo(ethylene glycol)-containing SAMs resist the adsorption of protein from solution and suggests that SAMs will be a useful model system for studying the adsorption of proteins onto organic surfaces.