Improving the dispersity of detonation nanodiamond: differential scanning calorimetry as a new method of controlling the aggregation state of nanodiamond powders

• Published in: Nanoscale Vol. 5; no. 4; pp. 1529 - 1536
• Main Authors: Korobov, Mikhail V, Volkov, Dmitry S, Avramenko, Natalya V, Belyaeva, Lubov' A, Semenyuk, Pavel I, Proskurnin, Mikhail A
• Format: Journal Article
• Language: English
• Published: England 01.01.2013
• Subjects: Agglomeration; Calorimetry, Differential Scanning - methods; Colloids - chemistry; Crystallization - methods; Detonation; Diamond - chemistry; Diamonds; Differential scanning calorimetry; Dispersions; Drying; Gels; Hot Temperature; Macromolecular Substances - chemistry; Materials Testing; Molecular Conformation; Nanostructure; Nanostructures - chemistry; Nanostructures - ultrastructure; Particle Size; Powders; Surface Properties
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c2nr33512c

Detonation nanodiamond (ND) is a suitable source material to produce unique samples consisting of almost uniform diamond nanocrystals ( d = 3-5 nm). Such samples exist in the form of long stable aqueous dispersions with narrow size distribution of diamond particles. The material is finding ever increasing application in biomedicine. The major problem in producing monodispersed diamond colloids lies in the necessity of deagglomeration of detonation soot and/or removing of clusters formed by already isolated core particles in dry powders. To do this one must have an effective method to monitor the aggregation state or dispersity of powders and gels prior to the preparation of aqueous dispersions. In the absence of dispersity control at various stages of preparation the reproducibility of properties of existing ND materials is poor. In this paper we introduce differential scanning calorimetry (DSC) as a new tool capable to distinguish the state of aggregation in dry and wetted ND materials and to follow changes in this state under different types of treatment. Samples with identical X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) images gave visibly different DSC traces. Strong correlation was found between dynamic light scattering (DLS) data for colloids and DSC parameters for gels and powders of the same material. Based on DSC data we improved dispersity of existing ND materials and isolated samples with the best possible DSC parameters. These were true monodispersed easily dispersible fractions of ND particles with diameters of ca. 3 nm. Differential Scanning Calorimetry (DSC) is introduced as a new powerful tool to monitor the aggregation state of nanodiamond powders and to predict the quality of aqueous colloids.