The arrangements of colloidal particles on solid substrates play a crucial role in many applications such as inkjet printings, coatings, films, and lithography. To further develop functions of colloidal arrays such as optical properties, water repellency and biocompatibility, precise control of arrangements is required. The controlled evaporation of sessile droplets is the simplest and most cost-effective method to produce the ordered colloidal arrays on solid substrates[1-3]. In the present study, we found that soft and deformable elastomer microspheres can form non-close-packed structures partially on solid substrates after evaporation of water from aqueous sessile droplets without any complex treatment such as an exposure of plasma or heat[4]. The elastomer microspheres adsorbed at the air/water interface and formed an ordered structure at intervals. The arrangements at the interface were transferred onto the solid substrates during drying without disruption (Figure). This result indicates that the deformability of elastomer microspheres is important for formation of non-close-packed structures. Furthermore, the non-close-packed structures over large area were achieved by Langmuir-Blodgett method by lifting the substrate from air/water interface. By tuning the surface pressure, the non-close-packed structures in the resultant monolayer film were adjusted. Our findings of this study would promote further development in arrangement of colloidal particles.

Non-close-packed arrays of soft elastomer microspheres through evaporation of aqueous droplets on solid substrates

ACS Fall 2021

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