The role of modifying molecular chains in the formation of organized molecular films of organo-modified nanodiamond: construction of a highly ordered low defect particle layer and evaluation of desorption behavior of organic chains.

The role of organo-modifying molecular chains in the formation of molecular films of organo-modified nanodiamond is discussed herein based on interfacial chemical particle integration of organo-modified nanodiamond having a particle size of 5 nm. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water. This water nanolayer was exploited for organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersion of nanodiamond in general organic solvents as a mimic of solvency. The organo-modified nanodiamond dispersed "solution" was used as a spreading solution for depositing a mono-"particle" layer on the water surface, and a Langmuir particle layer was integrated at the air/water interface. Multi-"particle" layers were then formed via the Langmuir-Blodgett technique and were subjected to fine structural analysis. The effect of organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. That is to say, the "encounter" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles, which can be regarded as imparting new function to the organic molecules. The morphology of the single-particle layer was maintained after removal of the organic region of the composite via the baking process, whereas the regularity of the layered period was disordered. Thus, the organic chains are essential as modifiers for maintenance of the layered structure.