PH-switchable stratification of colloidal coatings: surfaces "on demand"
journal contributionposted on 2017-02-02, 16:25 authored by Ignacio Martin-Fabiani, Andrea Fortini, Jennifer Lesage de la Haye, Ming L. Koh, Spencer E. Taylor, Elodie Bourgeat-Lami, Muriel Lansalot, Franck D'Agosto, Richard P. Sear, Joseph L. Keddie
Stratified coatings are used to provide properties at a surface, such as hardness or refractive index, which are different from underlying layers. Although time-savings are offered by self-assembly approaches, there have been no methods yet reported to offer stratification on demand. Here, we demonstrate a strategy to create self-assembled stratified coatings, which can be switched to homogeneous structures when required. We use blends of large and small colloidal polymer particle dispersions in water that self-assemble during drying because of an osmotic pressure gradient that leads to a downward velocity of larger particles. Our confocal fluorescent microscopy images reveal a distinct surface layer created by the small particles. When the pH of the initial dispersion is raised, the hydrophilic shells of the small particles swell substantially, and the stratification is switched off. Brownian dynamics simulations explain the suppression of stratification when the small particles are swollen as a result of reduced particle mobility, a drop in the pressure gradient, and less time available before particle jamming. Our strategy paves the way for applications in antireflection films and protective coatings in which the required surface composition can be achieved on demand, simply by adjusting the pH prior to deposition.
European Union Seventh Framework Programme BARRIER-PLUS project (FP7-SME-2012-2, No. 304758).
- Aeronautical, Automotive, Chemical and Materials Engineering
Published inACS Applied Materials and Interfaces
Pages34755 - 34761
CitationMARTIN-FABIANI, I. ... et al, 2016. PH-switchable stratification of colloidal coatings: surfaces "on demand". ACS Applied Materials and Interfaces, 8 (50), pp. 34755-34761.
Publisher© American Chemical Society
- AM (Accepted Manuscript)
Publisher statementThis work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/
NotesThis document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acsami.6b12015.