title: Layers over layer-by-layer assemblies: silanization of polyelectrolyte multilayers.
abstract: The functionalization of poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) polyelectrolyte multilayers by silanes reacted from the gas phase is studied depending on reaction time and temperature, pH of multilayer assembly, and nature of the reacting silane group. Whereas monochlorosilanes only diffuse in the multilayer and graft in limited amount, trichloro- and triethoxysilanes form rapidly a continuous gel layer on the surface of the multilayer, with a thickness of ca. 10-20 nm. The reactivity is lower in the strongly paired regime of the multilayers (neutral assembly conditions) but otherwise is not affected by the pH of multilayer assembly. Silanization considerably broadens the range of possible functionalities for (PAH/PAA) multilayers: hydrophobicity, surface-initiated polymerization, and grafting of fluorescent probes by the formation of disulfide bridges are demonstrated. Conversely, our results also broaden the range of substrates that can be functionalized by silanes, using (PAH/PAA) multilayers as ubiquitous anchoring layers.
authors.affiliation: Bio & Soft Matter, Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain , Croix du Sud 1 L7.04.02, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Ali
authors.initials: A
authors.lastname: Dirani
authors.forename: Antony E
authors.initials: AE
authors.lastname: Fernandes
authors.forename: Diana Ramirez
authors.initials: DR
authors.lastname: Wong
authors.forename: Pascale
authors.initials: P
authors.lastname: Lipnik
authors.forename: Claude
authors.initials: C
authors.lastname: Poleunis
authors.forename: Bernard
authors.initials: B
authors.lastname: Nysten
authors.forename: Karine
authors.initials: K
authors.lastname: Glinel
authors.forename: Alain M
authors.initials: AM
authors.lastname: Jonas