Surface and friction forces between grafted polysaccharide layers in the absence and presence of surfactant
2011 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 364, 351-358 p.Article in journal (Refereed) Published
We analyzed the interaction between chemically grafted polysaccharide layers in aqueous solutions. To fabricate such layers, an end-terminated dextran silane coupling agent was synthesized and the polydextran was grafted to oxidized silicon wafers and to silica particles. This resulted in the formation of a 28 nm thick layer (in air) and a grafted amount of 40 mg/m2 as determined by ellipsometry. The physical properties of the grafted layer were investigated in aqueous solutions by atomic force microscope imaging and colloidal probe force measurements. Surface and friction forces were measured between one bare and one polydextran coated silica surface. A notable feature was a bridging attraction due to affinity between dextran and the silica surface. Surface interactions and friction forces were also investigated between two surfaces coated with grafted polydextran. Repulsive forces were predominant, but nevertheless a high friction force was observed. The repulsive forces were enhanced by addition of sodium dodecyl sulfate (SDS) that associates with the tethered polydextran layers. SDS also decreased the friction force. Our data suggests that energy dissipation due to shear-induced structural changes within the grafted layer is of prime importance for the high friction forces observed, in particular deformation of protrusions in the surface layer.
Place, publisher, year, edition, pages
2011. Vol. 364, 351-358 p.
Dextran, Silane coupling agent, Polymer layer, Silica, Friction, Surface forces, Adhesion, Tethered polysaccharide, AFM, Ellipsometry
IdentifiersURN: urn:nbn:se:kth:diva-48445DOI: 10.1016/j.jcis.2011.08.065ISI: 000296223500010ScopusID: 2-s2.0-80054698391OAI: oai:DiVA.org:kth-48445DiVA: diva2:457628
QC 201111212011-11-182011-11-182012-01-18Bibliographically approved