Nanocomposites and nanomaterials

Formation of critical concentration values in nanosized silica – polymer thin coatings
Myronyuk O.V.1, Raks V.A. 2, Sivolapov P.V. 1 Baklan D.V. 1 Konoplitska O.P. 2
1 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Chemical Technology Faculty Peremohy Ave, 37, Kyiv-03056, Ukraine. 
E-mail: o.myronyuk@kpi.ua
2 Taras Shevchenko National University of Kyiv, Faculty of Chemistry Lva Tolstoho Street, 12, 01033, Kyiv, Ukraine.

The performance of thin layer superhydrophobic coatings is determined by the structural organization of it’s interface, which can be controlled by simply the ratio between the carrier and nanoparticles. There is the critical concentration of the filler, which corresponds to a rapid shift of the coating’s surface to a superhydrophobic state. In previous work [1] it was shown that the position of the critical point substantially depends on the specific surface of the filler. 
The aim of this study was the determination of a film-forming polymer effect on the position of the aforementioned critical point. 
The study conducted on systems, which include nanosized silica, treated with dimethyldichlorosilane and various polymers from acrylate, cellulose acetate, styrene containing groups etc. 
It was shown, that variation of matrix material leads to significant change in critical concentrations. For example, in case of styrenebythylmetacrylate the critical point is situated at 3,5 wt. % of nanoscale filler, but in case of cellulose acetate-butyrate, it shifts to 32 wt. %. This effect may be attributed to a different cluster organization in both cases, caused by a difference in wetting behavior, surface affinity of materials etc.
The major effect of this founding is the possibility to change the position of the superhydrophobic shift. And it may be helpful in the solution of the issue of the mechanical weakness of such structures.

1.	Raks V., Myronyuk O., Prydatko A. Large-Scale Solution for Superhydrophobic Surfaces //Nanophysics, Nanophotonics, Surface Studies, and Applications. Springer Proceedings in Physics. 2016, 183, P. 247-259