title: Tribological properties of poly(L-lysine)-graft-poly(ethylene glycol) films: influence of polymer architecture and adsorbed conformation.
abstract: The tribological properties of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG)-coated oxide interfaces have been investigated with atomic force microscopy (AFM) as a function of the molecular structure. Polymer-bearing surfaces were obtained via spontaneous adsorption of the polymer onto the oxide substrate from a buffered solution of physiological pH. Interfacial friction of these PLL-g-PEG-coated surfaces was found to be highly dependent on the duration of deposition and the architecture of PLL-g-PEG. In terms of the architecture, the PEG chain length and the grafting ratio (i.e., the molar ratio of L-lysine monomer to PEG side chain) of adsorbed PLL-g-PEG significantly influence the interfacial friction; specifically, friction is reduced as the PEG chain length increases and as the molar ratio of L-lysine monomer to PEG side chain decreases. The characteristics of the polymer deposition time and the influence of the lysine/PEG grafting ratio are rationalized in terms of spatial packing density considerations.
authors.affiliation: Departments of Materials Science & Engineering and of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Scott S
authors.initials: SS
authors.lastname: Perry
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Yan
authors.forename: F T
authors.initials: FT
authors.lastname: Limpoco
authors.forename: Seunghwan
authors.initials: S
authors.lastname: Lee
authors.forename: Markus
authors.initials: M
authors.lastname: Müller
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Spencer