Hydrophobicity and Adhesion of Aggregated Diamond Particles

Diamond powders with high hydrophobicity are prepared by etching graphite plates using a hydrogen/argon (H-2/Ar) plasma. The morphology and size of the diamond powders are found to vary with the proportion of Ar in H-2 from 0% to 50%. Wettability is measured using water contact angle (WCA) measurements giving values between 129.7 degrees and 146.9 degrees. The high hydrophobicity can be ascribed to the aggregated structure of the as-grown diamond powders. To check this assumption, the aggregated diamond powders are separated into individual particles by mechanical grinding; then, the WCAs of separated as-grown diamond powders and commercial dispersed diamond powders are compared. The separated diamond surfaces show the lower WCAs of 99.68 degrees and 96.96 degrees. The surface of the aggregated diamond powders also exhibits high adhesion to water. The diamond surface grown in 2% Ar suspends 40 mu L of water under a tilt angle of 180 degrees. Such aggregated diamond powders are promising for no-loss liquid transportation.