Artificial Petal Effect on Nanofibrillar Parylene™ Surface

The hierarchical structure on a rose petal surface achieves a large contact angle with high contact angle hysteresis. Inspired by the petal effect, two types of artificial structures, fibril mesh and fibril microhills, were fabricated and compared with the rose petal surface. The fibril mesh, composed of Parylene (TM) nanofibrils and underneath capillary structures was fabricated using template-assisted deposition. The fibril microhills were formed by peeling the fibril mesh off. The contact angle and contact angle hysteresis on these two surfaces treated by various surface modifications for enhancing the hydrophobicity were measured. The fabricated surface showed similar wetting behavior to the rose petal which is hydrophobic and sticky to water droplets. The relation between the contact angle and the contact angle hysteresis on the various artificial surfaces and the rose petal were discussed. The qualitative estimations of the contact angle hysteresis for the various artificial surfaces were presented.