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Ionic Surfactant Binding to pH-Responsive Polyelectrolyte Brush-Grafted Nanoparticles in Suspension and on Charged Surfaces
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
2015 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 51, 13680-13689 p.Article in journal (Refereed) PublishedText
Abstract [en]

The interactions between silica nanoparticles grafted with a brush of cationic poly(2-(dimethylamino) ethyl methacrylate) (SiO2-g-PDMAEMA) and anionic surfactant sodium dodecyl sulfate (SDS) is investigated by dynamic light scattering, electrophoretic mobility, quartz crystal microbalance with dissipation, ellipsometry, and atomic force microscopy. SiO2-g-PDMAEMA exhibits pH-dependent charge and size properties which enable the SDS binding to be probed over a range of electrostatic conditions and brush conformations. SDS monomers bind irreversibly to SiO2-g-PDMAEMA at low surfactant concentrations (similar to 10(-4) M) while exhibiting a pH-dependent threshold above which cooperative, partially reversible SDS binding occurs. At pH 5, SDS binding induces collapse of the highly charged and swollen brush as observed in the bulk by DLS and on surfaces by QCM-D. Similar experiments at pH 9 suggest that SDS binds to the periphery of the weakly charged and deswollen brush and produces SiO2-g-PDMAEMA/SDS complexes with a net negative charge. SiO2-g-PDMAEMA brush collapse and charge neutralization is further confirmed by colloidal probe AFM measurements, where reduced electrosteric repulsions and bridging adhesion are attributed to effects of the bound SDS. Additionally, sequential adsorption schemes with SDS and SiO2-g-PDMAEMA are used to enhance deposition relative to SiO2-g-PDMAEMA direct adsorption on silica. This work shows that the polyelectrolyte brush configuration responds in a more dramatic fashion to SDS than to pH-induced changes in ionization, and this can be exploited to manipulate the structure of adsorbed layers and the corresponding forces of compression and friction between opposing surfaces.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015. Vol. 31, no 51, 13680-13689 p.
Keyword [en]
ATOMIC-FORCE MICROSCOPE, COLLOIDAL PARTICLES, POLYMER BRUSHES, STAR POLYMERS, ADSORPTION, INTERFACE, MIXTURES SILICA, ELECTROPHORESIS, DENDRIMERS
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-181379DOI: 10.1021/acs.langmuir.5b03757ISI: 000367559700007PubMedID: 26649483ScopusID: 2-s2.0-84952815398OAI: oai:DiVA.org:kth-181379DiVA: diva2:900288
Funder
Swedish Research Council
Note

QC 20160203

Available from: 2016-02-03 Created: 2016-02-01 Last updated: 2016-02-05Bibliographically approved

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