Mudassar Mumtaz Virk, Peter D J van Oostrum
Institute of Colloid and Biointerface Science (ICBS)
BOKU University
Vienna, Austria
Inverse patchy colloids (IPCs) are nano-to-microscale particles characterized by distinct oppositely charged regions, or "patches," on their surfaces [1]. This inhomogeneous charge distribution leads to orientation-dependent attractive and repulsive interactions between particles, giving rise to rich self-assembly patterns influenced by external parameters like pH and salt concentration [2]. Here, we introduce a novel and simple method for synthesizing silica-based IPCs with two positively charged patches based on the triboelectric effect. To facilitate the visualization of patches via confocal and scanning electron microscopy, the positive patches were labeled with fluorescent dyes and gold nanoparticles respectively. To prevent particles from entering the van der Waals attraction region and minimize steric interactions, the IPCs were also coated with the neutral polymer, Pluronic F-127. This coating promotes colloidal stability while maintaining the selective attraction between the patchy and non-patchy regions via overlapping electric double layers. We investigated the self-assembly behavior of IPCs in function of the pH which tunes the relative charges at a fixed salt concentration [3]. Our method provides a simple yet versatile approach for synthesizing IPCs for studies in colloidal science and materials engineering.
[1] Virk et al, J. Phys.: Condens. Matter 35 174003 (2023)
[2] E. Bianchi et al, Current Opinion in Colloid & Interface Science, 30, 18 (2017)
[3] Virk et al, in preparation