Honeycomb pattern formation on poly(vinyl chloride) films: electrically-driven microparticle trapping and the effect of drying temperature

Abstract

This work presents the effect of drying temperature on the formation of poly(vinyl chloride) (PVC) honeycomb microstructures formed by the breath figure technique. Results revealed the self-assembly of honeycomb patterns with small cell diameter and thick cell walls dried at room temperature. An increase in cell diameter and a decrease in wall thickness were observed as drying temperature was increased up to 70 °C while no formation of patterns was noted at temperatures greater than or equal to 80 °C. The presence of honeycomb patterns consequently enhanced the static water contact angle of the PVC layer. Electrowetting experiments revealed more pronounced reduction in the water contact angle on honeycomb-structured PVC compared to a flat PVC layer at any given applied voltage. A proof-of-concept on the feasibility of the honeycomb structures to trap microparticles by electrically-driven droplet actuation was further demonstrated. Corresponding SEM images confirmed the entrapment of microparticles in the honeycomb cells and walls after the electrowetting experiment. These results offer new and facile strategies for tuning the morphological properties of polymeric honeycomb microstructures and its possible application in microparticle trapping and sensing.

Keywords

• drying temperature
• honeycomb microstructure
• poly(vinyl chloride)
• contact angle
• electrowetting