SKM 2023 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: Crystallization, Nucleation and Self-Assembly
CPP 19.10: Talk
Tuesday, March 28, 2023, 12:15–12:30, MER 02
Controlling internal structure of colloidal supraparticles - crystalline to amorphous — •Yashraj Wani1, Melis Yetkin2, Michael Kappl2, Hans-Jürgen Butt2, and Arash Nikoubashman1 — 1Institute of Physics, JGU Mainz, Germany — 2Max Planck Institute for Polymer Research, Mainz, Germany
Colloidal supraparticles made from smaller nanoparticles (NPs) are versatile materials whose properties can be tailored through the chemistry and ordering of their constituent NPs. Such supraparticles can be scalably fabricated using solvent-drying processes that assemble NPs inside liquid droplets. In charge stabilized dispersions, the interactions can be controlled by the salt concentration, which we systematically probed in experiments and simulations. In experiments at low salt concentrations, the dried supraparticles exhibited high crystalline order, whereas amorphous structures were found at high salinity. To understand this evaporation-induced structure formation, we first determined the interaction potentials between NPs via colloidal probe atomic force microscopy and dynamic light scattering experiments. Using these pair potentials, we carried out particle-based simulations to study the aggregation behavior in detail: At low salt concentrations, the effective NP-NP interactions remained purely repulsive until the end of drying, resulting in highly crystalline supraparticles. At higher salt concentrations, however, the electrostatic repulsion became screened, leading to the formation of small NP aggregates at early stages of drying, which then eventually merged into an amorphous supraparticles.