Physical and Chemical Problems of Modification of Detonation Nanodiamond Surface Properties

Abstract

A wide application of detonation nanodiamonds is hampered by their low purity and difficulties of making stable nanodiamond suspensions. These problems have not been adequately dealt with in available publications. Here we present an integrated conception of the nanodiamond structure and offer a practical solution to some of these problems. A detailed description and a schematic illustration of the detonation nanodiamond structure are presented. The structure-forming effect of nanodiamond particles on the ambient is interpreted. The pH of an aqueous suspension of nanodiamonds is determined and their behavior as a function of the pH is shown. We also analyse the mechanism of a prolonged water washing to remove excessive acidity, a factor determining the chemical purification time. A method is offered to improve essentially the quality of nanodiamonds and the stability of their aqueous suspensions by treating them with ammonia water (to an alkalescent medium), followed by heating to 200-240 degrees C under pressure (so called "thermolysis").