Thermal stability of ordered multi-particle layers of long-chain phosphonate-modified nanodiamond with superior heat-resistance

Abstract The maintenance properties of the layered regularity in organized films of heat-resistant, organo-modified nanodiamond upon heating were investigated. In long-chain phosphonic acid-modified nanodiamond, desorption of the modified-molecular chain due to temperature elevation was suppressed until 350 °C. This innovative improvement is compared to the desorption behavior at 155 °C of chains of stearic acid-modified nanodiamond. When two-dimensional films with layered organization were formed, clear layered periods were observed, and it was simultaneously confirmed that unmodified-chain impurities could not be removed. Temperature-controlled X-ray diffraction and IR measurements showed that impurities could be fired and removed. Due to the annealing effect during heating above 100 °C, the layered order was enhanced owing to rearrangement of the organo-nanodiamonds. The layered regularity of the organo-particle layers during heating was maintained up to 175 °C, far exceeding the value of 50 °C of the organized film of stearic acid-modified nanodiamond. This technique is expected to be developed for single-layer coating on the outermost layer of a surface with a nanodiamond, which has excellent antibacterial properties and high refractive index and thermal conductivity.