title: Single-molecule tracking of polymer surface diffusion.
abstract: The dynamics of polymers adsorbed to a solid surface are important in thin-film formation, adhesion phenomena, and biosensing applications, but they are still poorly understood. Here we present tracking data that follow the dynamics of isolated poly(ethylene glycol) chains adsorbed at a hydrophobic solid-liquid interface. We found that molecules moved on the surface via a continuous-time random walk mechanism, where periods of immobilization were punctuated by desorption-mediated jumps. The dependence of the surface mobility on molecular weight (2, 5, 10, 20, and 40 kg/mol were investigated) suggested that surface-adsorbed polymers maintained effectively three-dimensional surface conformations. These results indicate that polymer surface diffusion, rather than occurring in the two dimensions of the interface, is dominated by a three-dimensional mechanism that leads to large surface displacements and significant bulk-surface coupling.
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Skaug
authors.forename: Joshua N
authors.initials: JN
authors.lastname: Mabry
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Schwartz
mesh_terms: D000327:Adsorption; D004058:Diffusion; D007700:Kinetics; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D011092:Polyethylene Glycols