Nanocomposites and nanomaterials

Functionalization of montmorillonite and synthesis on the surface of nanoparticles for creating nanofillers forpolar polymers
Gonchar O.M.
Institute of Macromolecular Chemistry NAS of Ukraine. Kharkovskoe shosse 48, 02160, Kiev, Ukraine.
E-mail: lexgon@ukr.net

To create nanocomposites based on various types of polar polymers with montmorillonite (MMT), a method was developed to modify the surface of MMT by the cationic oligourethane with available amino groups. Cationic oligourethane (oligourethane amine ammonium chloride - OUAAC) was synthesized based on N-methyl diethanolamine and an aliphatic diisocyanate - 1,6-hexamethylene diisocyanate. As a result of simple synthesis, an aqueous solution of OUAAC with a concentration of 4.5×10-3 mol/l was obtained.  
The macromolecules OUAAC contains available, terminal amino groups in its composition were investigated by IR spectroscopy. To determine the content of amino groups, acid-base titration of the resulting aqueous solution of OUAAC was carried out. MMT from the Cherkasy deposit was used with an exchange capacity of 0.65×10-3 mol/g, which was converted to the sodium form. Modification of the sodium form of MMT was carried out with an aqueous solution of OUAAC in an aqueous suspension. The obtained modified MMT was isolated and studied by thermal gravimetric analysis to determine the organic component, which amounted to 24% wt. Modified OUAAC MMT forms a stable suspension in dimethylformamide medium after sonication. In a suspension of modified MMT additional reactions of aromatic and aliphatic diisocyanates were carried out, as well as sequential addition of aromatic diisocyanate, glycerol, and diisocyanate again. Thus, the possibility of synthesis on the surface of MMT  of nanoparticles was demonstrated. Using the WAXS method, the interlayer distance of all types of the obtained modified montmorillonite was determined. The addition of diisocyanates corresponding to the content of amino groups was proved by thermal gravimetric analysis. MMT modified with OUAAC opens up great opportunities for the design of the organic layer on the surface of nanoparticles using both diisocyanates and other functional compounds, such as anhydrides and others. The use of MMT with a reactive surface opens up enormous opportunities in the creation of hybrid organic/inorganic nanocomposites based on polar polymers.