Maintenance property of layered regularity in multi-particle layers of fluorinated phosphonate-modified nanodiamond under the heating

Maintenance of the layered regularity in organized particle films of fluorinated chain-modified nanodiamond (ND) with excellent heat resistance under heating was investigated. In fluorinated phosphonic acid-modified ND, desorption of the modified-chain by temperature elevation was suppressed up to 300 degrees C. The fluorinated long chain phosphonate-modified ND formed a stable single-particle film on the water surface, and the multilayers exhibited high layered regularities. This compound had remarkably improved water repellency on the surface at the level of a single-layer film. However, its heat resistance temperature was less than 100 degrees C. The layered regularity, which is easily disturbed on heating, was predicted to be caused by multiple defects in the particle packing in the plane. Therefore, during the formation of a monolayer on the surface of the fluorinated long-chain phosphonate-modified ND, compression and expansion were performed multiple times to promote rearrangement of the particles. As a result, the packing density of the particles in the plane and the maintenance of the layered order improved. In comparison, the layered order of stearyl phosphonate-modified ND was maintained up to 175 degrees C; hence, it was suggested that the packing of the modified-fluorinated chains comprised bidentate bonds and that weak van der Waals interactions were relatively sparse.