title: Wettability of terminally anchored polymer brush layers on a polyamide surface.
abstract: Surface wettability of terminally anchored hydrophilic polymer brush layers on polyamide-silicon (PA-Si) surfaces was evaluated with respect to surface topography at the nanoscale. Hydrophilic polyvinylpyrrolidone (PVP) and polyacrylamide (PAAm) brush layers were synthesized via graft polymerization onto a PA-Si surface previously activated by surface treatment with atmospheric pressure plasma. Hydrophilicity (or wettability) of the PA substrate, as quantified by the free energy of hydration, was increased upon surface coverage with the PVP and PAAm brush layers by 13-24% (-101.4 to -111.3 mJ/m(2)) and 19-37% (-106.1 to -122.4 mJ/m(2)), respectively. Surface hydrophilicity increased with both increasing surface roughness (0.55-2.89 nm and 1.54-5.84 nm for PVP and PAAm, respectively) and polymer volume (1.3×10(6)-7.3×10(6) nm(3)/μm(2) and 3.3×10(6)-2.8×10(7) nm(3)/μm(2) for PVP and PAAm surfaces, respectively). The present study suggests that a specific level of surface wettability can be attained by tailor-designing the polymer brush layer's physicochemical characteristics (e.g., surface roughness, wettability, and polymer water affinity) by adjusting surface topography and surface chemistry, which are controlled by surface activation and polymerization conditions. The above indicates that there is merit in structuring various surfaces with hydrophilic brush layers to increase surface wettability in membrane filtration, biomedical devices, and lubrication applications.
authors.affiliation: University of California, Los Angeles, Department of Chemical and Biomolecular Engineering, 5531 Boelter Hall, Los Angeles, CA 90095-1592, United States. Electronic address: kvarin@ucla.edu.
authors.forename: Kari J Moses
authors.initials: KJ
authors.lastname: Varin
authors.affiliation: University of California, Los Angeles, Department of Chemical and Biomolecular Engineering, 5531 Boelter Hall, Los Angeles, CA 90095-1592, United States. Electronic address: yoram@ucla.edu.
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen
mesh_terms: D018625:Microscopy, Atomic Force; D009757:Nylons / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D017155:Wettability
chemical_list: D009757:Nylons; D011108:Polymers
keywords: Atmospheric pressure plasma; Graft polymerization; Surface roughness; Wettability