Nanofillers Densil and Sol-Densil. Preparation technology.

During long time, the staff at the Chuiko Institute of Surface Chemistry (CISC) carried out the investigations of the physicochemical properties and characteristics of fumed metal or metalloid oxides (FMO), e.g. nanosilica, nanoalumina, nanotitania, and complex nanooxides, which are synthesized using the Aerosil process. Nanosilicas with trade names AerosilR (Evonik Degussa, Germany), HDK (Wacker-Chemie GmbH, Germany), Cab-O-Sil (Cabot Corporation, USA), pyrogenic silica Orisil (Orisil, Ukraine), etc. are widely used in industry, medicine, agriculture, science, etc. as fillers of various systems, especially polymers.

To improve some properties of FMO (e.g. to reduce the dust-forming effect), we developed nanosilica-based materials Densil and Sol-Densil using a method of geometrical modification of silica.

Densil is a product of the geometrical modification of nanosilica mechanically treated in the gaseous dispersion media. This modification results in strong changes of the material with respect its macro- and micro-levels (Table 1). The most obvious change deals with changes in the bulk density of the material(Fig.1).

The characteristics of Densil could be varied depending on the modification conditions (Table 1).

A low thickening power of Densil is an important characteristic. The gelation of the aqueous suspension of Densil could occur at the content of ca. 50 wt.% (Table 1). This property allows to prepare highly Densil-filled of polymers.

Lower osmotic activity and high gelation point of Densil in comparison to unmodified nanosilica provide perspectives in the use of Densil as a medical sorbent for purification of wounds. It can be used both on the first and second stages of the wound treatment with no a risk of wound over-drying and formation of inpervious tight films on the wounds.

Sol-Densil is a modified Densil, which can be surface covered by a sub- or monolayer or clusters of inorganic salts, metals, e.g. silver nitrate, silver iodide, metallic silver, copper sulphate or oxide, sodium chloride or phosphate, etc. The surface modifiers in Sol-Densil are in highly disperse, nanosized state (Fig. 2)

Sol-Densil could be applied in various systems as:

• a filler of lacquers and paints, polymers, etc. to add anti-bacterial and other properties (characteristic for a salt, metal, oxide used to modified Densil) of the final materials;
• a component of extinguishant powders;
• a base of ice-forming reagents for precipitation of supercooled fog and clouds;
• a substance for creation of medicinal preparations with sorption activity.

The pilot technology was developed to produce nanomaterials Densil and Sol-Densil.

There are the regulatory documents:

• Complex Reagents Sol-Densil. Technical conditions. TU U 20.1-03291669-019:2013.
• Resolution of the state sanitary-epidemiological expertise.
• Temporary technological regulation 03291669-2012№ TTR.

Current development status

Others

Available for demonstration, there are test samples and lots

Desired business relationship

Joint ventures

Technology development

New technology applications

Adaptation of technology to other markets

Products developed on the base of Densil and Sol-Densil

Powdered ice-forming reagent for weather modification by cloud seeding, as well as to prevent hail

According to the order of S.R.L. "Protect-Grindina" (Moldova), a pilot batch of powdered ice-forming nanoscale reagent (AgI (10 wt.%)/SiO2, amount of 10 kg, Fig. 3) was prepared to carry out the natural experiment.

- Sosnikova E.V., Plaude N.O., Voronin E.F., Nosach L.V., Pakhlov E.M., Gun’ko V.M., Pokrovsky V.A. Investigation of the efficiency of nanoscale crystallizing AgI/SiO2 reagents. Problems of the physics of clouds. Atmospheric aerosols, active effects. Col. articles memory of N.O.Plаude. Obninsk: FGBU "VNIIGMI-WDC", 2015, p.p. 323-330 (in Russian).

- Sosnikova E.V., Danelyan B.G., Voronin E.F., Nosach L.V., Pakhlov Е.М., Gun’ko V.M., Pokrovsky V.А. Nanoscale crystallizing reagent AgI/SiO2, efficiency study. Rep. of All-Russian Open Conference on the Physics of Clouds and Active Influence on Hydrometeorological Processes, dedicated to the 80th anniversary of the Elbrus Highland Complex Expedition of USSR Academy of Sciences, 2014, Part. 2, Nalchik, 2015, p.p. 195-201 (in Russian).

- Eugeny F. Voronin, Liudmyla V. Nosach, Vladimir M. Gun’ko, Elena V. Sosnikova, Bagrat G. Danelyan, Barbara Charmas. Properties and Advantages of Powdered Ice-Forming Reagents Based on Nanoscale Silica – Journal of the Georgian Geophysical Society, Issue A. Physics of Solid Earth, v.20A, 2017, pp. 72-79.

Anti-bacterial and anti-microbic enterosorbent with nanosilver/nanosilica

A nanocompositeAg/SiO2 (Fig. 4) was created and studied. Its structural and antimicrobic characteristics were studied. It possesses high anti-microbic properties with respect to gram-negative and gram-positive micro-organisms. With respect to the amounts of pure silver and the effects on the formation of planktont, this composite is worse than pure silver nitrate. However, it is better with respect to the formation of biofilms. This suggests that the composite is characterized by prolonged bio-activity in comparison to silver alone.

- Savchenko D. S. Experimental justification of antimicrobial and sorption activity of enterosorbent with nanosilver. – The thesis for a Candidate of Pharmaceutical Sciences Degree by the speciality 14.03.05 – Pharmacology. – National University of Pharmacy of Ministry of Healthcare of Ukraine, Kharkiv, 2014. (in Ukrainian)

- Patent №69526 Ukraine. 2012. (in Ukrainian)

- Patent №68913 Ukraine. 2012. (in Ukrainian)

Anti-microbic nanofiller of polymers for medical applications

Using the developed preparation technology, nanosilica based composites were prepared by surface modification with silver nitrate, cooper sulphate, zinc sulphate or acetate, amino acids (glycine, lysine, histidine, tryptophan), and metronidazole.

Composites Sol-Densil containing different salts of zinc, cooper, and silver were tested with respect to antimicrobic activity. It was found that the samples containing the salts of zinc and silver are characterized by greater activity than the samples containing the cooper salts.

Thus, Densil as a filler can be used not only for medical applications but also to improve the physicomechanical characteristics of polymer matrices filled up to 20 wt.% of developed nanofillers.

- M.D. Zheliba, I.I. Gerashchenko, L.V. Karabanova, E.F. Voronin, R.M. Chornopyshchuk, T.P. Osolodchenko, M.I. Burkovskyi. Assessment of the Antimicrobial Activity of Polymer Materials with Added Nanosilica Modified by Silver Compounds. – IFMBE Proceedings, 2015, V.55, Р.264-267.

- L.V. Karabanova, Yu.P. Gomza, S.D. Nesin, O.M. Bondaruk, E.P. Voronin, L.V. Nosach. Nanocomposites based on multicomponent polymer matrices and nanofiller densil for biomedical application. – Nanophysics, Nanophotonics, Surface Studies and Applications. – Springer International Publishing, 2016. – р.451-475.

- Patent №97613 Ukraine. 2015. (in Ukrainian)