title: Association of anionic surfactant and physisorbed branched brush layers probed by neutron and optical reflectometry.
abstract: Pre-adsorbed branched brush layers were formed on silica surfaces by adsorption of a diblock copolymer consisting of a linear cationic block and an uncharged bottle-brush block. The charge of the silica surface was found to affect the adsorption, with lower amounts of the cationic polyelectrolyte depositing on less charged silica. Cleaning under basic conditions rendered surfaces more negatively charged (more negative zeta-potential) than acid cleaning and was therefore used to increase polyelectrolyte adsorption. The structure of adsorbed layers of the diblock copolymer was as determined by neutron reflectometry found to be about 70 nm thick and very water rich (97%). Interactions between the anionic surfactant sodium dodecylsulfate (SDS) and such pre-adsorbed diblock polymer layers were studied by neutron reflectometry and by optical reflectometry. Optical reflectometry was also used for deducing interactions between the individual blocks of the diblock copolymer and SDS at the silica/aqueous interface. We find that SDS is readily incorporated in the diblock copolymer layer at low SDS concentrations, and preferentially co-localized with the cationic block of the polymer next to the silica surface. At higher SDS concentrations some desorption of polyelectrolyte/surfactant complexes takes place.
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden. Electronic address: xiaoyanl@kth.se.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Liu
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden; SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm, Sweden.
authors.forename: Andra
authors.initials: A
authors.lastname: Dedinaite
authors.affiliation: Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Nylander
authors.affiliation: Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; The Nanometer Structure Consortium, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden.
authors.forename: Aleksandra P
authors.initials: AP
authors.lastname: Dabkowska
authors.affiliation: ISIS, STFC, Rutherford-Appleton Lab, R3 2.3 Chilton, Didcot OX11 0QX, United Kingdom. Electronic address: maximilian.skoda@stfc.ac.uk.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Skoda
authors.affiliation: Department of Polymer Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania.
authors.forename: Ricardas
authors.initials: R
authors.lastname: Makuska
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden; SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm, Sweden.
authors.forename: Per M
authors.initials: PM
authors.lastname: Claesson
keywords: Adsorption; Diblock copolymer; Neutron reflectivity; Optical reflectometry; Polyelectrolyte-surfactant complex; Polymer brush layer; SDS