From Passive to Active: Self-Propelled Colloids in Coatings Formulation and Film Formation.

Area of Science:

• Materials Science
• Colloid Science
• Soft Matter Physics

Background:

• Coatings are limited by passive ingredients, hindering control over ingredient distribution and functional properties.
• Lack of control over spatial distribution of formulation ingredients prevents optimization of key functional properties in coatings.

Purpose of the Study:

• To demonstrate the use of active, self-propelled constituents in coatings formulations.
• To establish a framework for harnessing active Janus colloids (JCs) to influence coating microstructure.

Main Methods:

• Introducing active Janus colloids (JCs) into coating formulations.
• Investigating the accumulation of JCs at coating interfaces by overcoming sedimentation and chemical gradients.
• Balancing timescales of fuel depletion and evaporation-induced assembly to control JC distribution.

Main Results:

• Active Janus colloids (JCs) successfully overcome sedimentation and chemical gradients to accumulate at coating interfaces.
• Controlling JC distribution within dried coatings is achieved by balancing fuel depletion and evaporation-induced assembly timescales.
• JCs at the top coating surface exhibit an orientational bias, with sub-equatorial orientation being most common.

Conclusions:

• Active Janus colloids offer a novel approach to overcome limitations in traditional passive coatings.
• This proof-of-concept study establishes a framework for developing functional coatings with tunable microstructures.
• The orientation-biased JCs could enable future advancements in smart and responsive coating technologies.