Electrostatically anchored branched brush layers
2012 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 44, 15537-15547 p.Article in journal (Refereed) Published
A novel type of block copolymer has been synthesized. It consists of a linear cationic block and an uncharged bottle-brush block. The nonionic bottle-brush block contains 45 units long poly(ethylene oxide) side chains. This polymer was synthesized with the intention of creating branched brush layers firmly physisorbed to negatively charged surfaces via the cationic block, mimicking the architecture (but not the chemistry) of bottle-brush molecules suggested to be present on the cartilage surface, and contributing to the efficient lubrication of synovial joints. The adsorption properties of the diblock copolymer as well as of the two blocks separately were studied on silica surfaces using quartz crystal microbalance with dissipation monitoring (QCM-D) and optical reflectometry. The adsorption kinetics data highlight that the diblock copolymers initially adsorb preferentially parallel to the surface with both the cationic block and the uncharged bottle-brush block in contact with the surface. However, as the adsorption proceeds, a structural change occurs within the layer, and the PEO bottle-brush block extends toward solution, forming a surface-anchored branched brush layer. As the adsorption plateau is reached, the diblock copolymer layer is 46-48 nm thick, and the water content in the layer is above 90 wt %. The combination of strong electrostatic anchoring and highly hydrated branched brush structures provide strong steric repulsion, low friction forces, and high load bearing capacity. The strong electrostatic anchoring also provides high stability of preadsorbed layers under different ionic strength conditions.
Place, publisher, year, edition, pages
2012. Vol. 28, no 44, 15537-15547 p.
Adsorption, Block copolymers, Brushes, Electrostatics, Friction, Ionic strength, Polyethylene oxides, Silica, Synthesis (chemical)
IdentifiersURN: urn:nbn:se:kth:diva-107330DOI: 10.1021/la3028989ISI: 000310664300015ScopusID: 2-s2.0-84868538507OAI: oai:DiVA.org:kth-107330DiVA: diva2:576031
FunderSwedish Research Council
QC 201212122012-12-122012-12-102014-12-09Bibliographically approved