Designer Nanoparticles as Robust Superlubrication Vectors
| Autor: | Jacob Klein, Weifeng Lin, Nir Kampf |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
General Physics and Astronomy 02 engineering and technology 010402 general chemistry 01 natural sciences Micelle Article surfactant micelles Pulmonary surfactant hydration lubrication homo-oligomeric micelles General Materials Science Lipid bilayer Liposome block copolymer micelles Bilayer Surface force micelles on surfaces General Engineering 021001 nanoscience & nanotechnology 0104 chemical sciences Chemical engineering wormlike micelles Lubrication Mica 0210 nano-technology phosphocholinated micelles |
| Zdroj: | ACS Nano |
| ISSN: | 1936-086X 1936-0851 |
| Popis: | Phosphatidylcholine lipid bilayers or liposomes at interfaces in aqueous environments can provide extremely efficient lubrication. This is attributed to the hydration lubrication mechanism acting at the highly hydrated phosphocholine-headgroup layers exposed at the outer surface of each bilayer. Micelles exposing such phosphocholine groups could be an attractive alternative to liposomes due to their much easier preparation and structure control, but all studies to date of surfactant micelles have revealed that at relatively low normal stresses the surface layers rupture and friction increases abruptly. Here, we examine surface interactions between three kinds of phosphocholine-exposing micelles with different designed structures: single-tail surfactant micelles, homo-oligomeric micelles, and block copolymer micelles. Normal and shear forces between mica surfaces immersed in solutions of these micelles were measured using a surface force balance. The adsorbed layers on the mica were imaged using atomic force microscope, revealing surface structures ranging from wormlike to spherical micelles. The block copolymer micelles showed relatively low coverage arising from their stabilizing corona and consequently poor lubrication (μ ∼ 10-1). In contrast, the surfactant and homo-oligomeric micelles fully covered the mica surface and demonstrated excellent lubrication (μ ∼ O(10-3)). However, while the boundary layer of single-tailed surfactant micelles degraded under moderate pressure, the homo-oligomeric micellar boundary layer was robust at all applied contact pressures in our study (up to about 5 MPa). We attribute the difference to the much greater energy required to remove a homo-oligomeric molecule from its micelle, resulting in far greater stability under pressure and shear. |
| Databáze: | OpenAIRE |
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