title: Influence of solutes on hydration and lubricity of dextran brushes.
abstract: The characteristic lubricity and non-fouling behavior of polymer brushes is critically dependent on the solvation of the polymer chains, as well as the chain-chain interactions. Dextran brushes have shown promise as non-toxic aqueous lubricant films, and are similar in composition  to natural lubricating systems, while their comparative simplicity allows for controlled preparation and fine characterization. This project entails measuring the solvation and lubricity of dextran brushes in the presence of additives which modify the inter-chain hydrogen bonding. The thickness  and refractive index of the film were measured during adsorption of the brush layer onto a silica substrate and the subsequent immersion in solutions of potassium sulfate and α, α-trehalose. We also studied the lubricity of the system as a function of normal loading using colloidal-probe  AFM. Both solutes are shown to have a minimal effect on the hydration of the brush while significantly reducing the brush lubricity, indicating that inter-chain hydrogen bonding supports the load-bearing capacity of polysaccharide brushes.
authors.affiliation: Laboratory for Surface Science and Technology, ETH Zurich Wolfgang-Pauli-Strasse 10 CH-8093, Zürich, Switzerland.
authors.forename: Tolga
authors.initials: T
authors.lastname: Goren
authors.forename: Rowena
authors.initials: R
authors.lastname: Crockett
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Spencer