Lilypad aggregation: localised self-assembly and metal sequestration at a liquid-vapour interface

Area of Science:

• Soft materials science
• Supramolecular chemistry
• Colloid science

Background:

• Spatially resolved soft materials like vesicles and microgels are promising for applications such as selective adsorption and microscale reaction vessels.
• Achieving spatiotemporal control over the aggregation of these materials remains a challenge.

Purpose of the Study:

• To develop a method for controlled aggregation of soft materials at the liquid-vapour interface.
• To investigate the mechanism and controlling factors of this novel aggregation process.

Main Methods:

• Combining nickel(II) chloride with a dipyridyl oligo(urea) ligand in a vapor-diffusion setup.
• Utilizing self-assembly and fusion of monodisperse colloids at the liquid-vapour interface.
• Developing a physical model to describe the aggregation process and surface energy influences.

Main Results:

• A localized spheroidal aggregate, termed "lilypad aggregation," was successfully formed at the liquid-vapour interface.
• The aggregation process is governed by specific surface energy conditions that prevent bulk aggregation or film formation.
• The final size and shape of the aggregate are determined by surface energies, which can be estimated by monitoring morphology.
• These lilypad aggregates effectively sequester metal ions from the surrounding solution and are easily collected.

Conclusions:

• Lilypad aggregation offers a novel route for controlled formation of soft material aggregates with potential applications in separation and microreactors.
• The process is tunable via surface energy, allowing for predictable control over aggregate characteristics.
• This method provides a simple yet effective way to create functional colloidal assemblies capable of metal sequestration.