title: Colloidal properties and behaviors of 3 nm primary particles of detonation nanodiamonds in aqueous media.
abstract: This study was aimed to reveal the principal colloidal properties of the aqueous dispersion of extremely small primary single-crystalline diamond particles in water. Together with the non-diamond layer, the size of the colloidal species is 2.8 ± 0.6 nm as found via DLS of the initial 5.00 wt/vol% hydrosol. Anionic dyes are readily adsorbed on the colloidal species. This is in line with the positive zeta-potential. The critical coagulation concentrations of the 0.19 wt/vol% nanodiamond hydrosol were determined with a set of inorganic electrolytes and anionic surfactants. The data are in line with the Schulze-Hardy rule for "positive" sols. The fulfillment of the lyotropic (Hofmeister) series was also observed for single-charged anions. The abnormal influence of alkali gives evidence of the acidic nature of the positive charge of the nanodiamond species. Application of acid-base indicators allows estimating the value of the interfacial electrical potential of the nanodiamond particles. Upon dilution from 5.00% to 0.01%, the colloidal system under study exhibits unusual changes. The average size increases ca. ten-fold as determined by DLS. The TEM images support this observation. At the same time, the viscosity drops. This phenomenon was explained in terms of the so-called periodic colloidal structures (colloidal crystals) in concentrated solutions.
authors.affiliation: Department of Physical Chemistry, Kharkov V. N. Karazin National University, Kharkov, 61022, Ukraine. mchedlov@yandex.ru.
authors.forename: N O
authors.initials: NO
authors.lastname: Mchedlov-Petrossyan
authors.forename: N N
authors.initials: NN
authors.lastname: Kamneva
authors.forename: A I
authors.initials: AI
authors.lastname: Marynin
authors.forename: A P
authors.initials: AP
authors.lastname: Kryshtal
authors.forename: E
authors.initials: E
authors.lastname: Ōsawa