Physico-Chemical nanomaterials science

Ultrasonication impact on the thermal stability of detonation nanodiamonds 
Panova A.N.1, Tsapyuk G.G.2, Diyuk V.E.2, Loginova O.B.1, 
Grishchenko L.M.2, Zakharova T.M.2, and Lisnyak V.V.2
1 V. Bakul Institute for Superhard materials of the NAS of Ukraine. Avtozavodskaya Str., 2, Kyiv-04074, Ukraine.

2 Chemical Department, Taras Shevchenko University of Kyiv. Volodymyrska Str., 64, Kyiv-01601, Ukraine. 
E-mail: tsapuk2017@ukr.net

Here we considered the influence of ultrasound on the thermal physical and chemical properties of detonation nanodiamonds of UDAG AMD 75 trademark. 
The kinetic aspect of the thermal stability of the investigated was nanodiamonds considered on the basis of data obtained in isothermal conditions [1]. The rate of oxidation was calculated from the model of "carbon in a beaker". It has been established that ultrasonication reduces the number of active reaction sites of the oxidation reaction on the surface of nanodiamonds particles.
TPD MS showed that ultrasound processing reduces the desorption rate of carbon dioxide from the surface of nanodiamonds at high temperatures. This treatment is the reason for aggregate energy heterogeneity of the nanodiamonds since reducing the content of the smallest particles by increasing the content of the larger ones. In fact, ultrasonication can decrease the number of surface defects. The latter increases the thermal stability of nanodiamonds. Kinetic measurements showed that at the initial and subsequent stages of the oxidative treatment with atmospheric oxygen the ultrasonicated nanodiamonds possess the increased thermal stability as compared with that of the starting, non-sonicated nanodiamonds. 

1.	Zabuga V.Ya., Bochechko O.O. et al. On multiwalled carbon nanotubes oxidation: Thermogravimetric, spectral and macrokinetic studies. // Mol Cryst Liq Cryst.-2018.-661.-P. 81-90.