Colloidal Tornadoes in a Vial under Gravitational Sedimentation

Jianrui Zhang,Markus Antonietti,Baris Kumru

doi:10.1021/acs.jchemed.0c01507

Jianrui Zhang, Markus Antonietti + Show 1 more

Open Access

https://doi.org/10.1021/acs.jchemed.0c01507

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Abstract

ollective motion in living matter is highly intriguing but can also be observed in charged colloidal systems. Collective motion observed in colloidal systems requires extensive material synthesis, external stimuli, and advanced characterization methods that might be highly costly to be employed for teaching. Besides that, colloidal systems can inherently possess dynamic movements. Generally, colloidal sedimentation is pictured as a linear movement, but under certain conditions autonomously activated sedimentation can be attained. In this demonstration, a simple formation of colloidal tornadoes will be explored by gravitational force as the sole stimulus. This demonstration is ideal for the general public for colloid chemistry learning, and these findings can be coupled to colloidal stability lectures.

Highlights

Collective motion in living matter is highly intriguing but can be observed in charged colloidal systems
It is here very helpful that living systems can be simplified down to the nanomicroscale, namely, to colloidal systems that are made up of nonbiological matter.[15]. This concept is highly related to colloidal stability and DLVO theory, which allows the interplay of the forces experienced by a dispersion in relation to surface charge, temperature, and dielectric constant
Graphitic carbon nitride (g-CN) is a basic metal-free polymeric semiconductor that is typically utilized as a heterogeneous photocatalyst for a variety of applications through a visible-light-induced photoredox cycle.[22−26] The synthesis of g-CN relies on thermal condensation of nitrogenrich monomers, resulting in a hydrophobic core composed of tri-s-triazine units and hydrophilic noncondensed edges with a negative overall

Summary

Introduction

Collective motion in living matter is highly intriguing but can be observed in charged colloidal systems. The interplay of attraction and repulsion in g-CN dispersions to generate dynamically coupled colloidal states under gravitational sedimentation conditions will be visualized. Specific masses of g-CN corresponding to concentrations of 0.05, 0.2, or 0.5 wt % are placed in water (3 mL) as well as acetone (3 mL) and sonicated in a sonic bath for 30 min to obtain colloidal suspensions, and the vials or cuvettes are first allowed to rest for 6 h only for the sedimentation of larger sheets.

Results

Conclusion