NANOCOMPOSITE HYDROGELS WITH EMBEDDED MINERAL NANOPARTICLES

Cross-linked nanocomposite hydrogels based on poly(acryl amide) and mineral nanoparticles (NP) of hydroxyapatite (HAP), ZnO, TiO2 modified by reactive polymers were synthesized via the technique of polymerization filling. It was shown that physico-mechanical properties of obtained nanocomposites are determined to a great extend by the nature of the modifier of mineral NP. So, in the case of nanocomposites based on HAP NP the sample based on unmodified HAP demonstrated the lowest thermo-mechanical resistance whereas the sample based on HAP NP modified by peroxide-containing copolymer did not soften even at T=405K that testified about the formation of highly structured and rigid nanocomposite material.

As a result of modification of TiO2 and ZnO NP by peroxidic modifiers mineral nanoparticles with thin adsorption polymer layer were obtained, peroxidic fragments of which are able to initiateradical processes. Modified in such a way nanoparticles were used as filler-initiator during the synthesis of nano-structured poly(acryl amide) hydrogels. In the case of absence of additional cross-linker the gel-fraction of obtained composites was low and structured hydrogel capable to swelling in water was not formed. Therefore, at the synthesis of filled cured hydrogels we introduced additional cross-linker – N,N' methylene-bis-acryl amide (MBA). As a result, cross-linked nanocomposite hydrogels with curing degree from 50% to 97% were obtained depending on NP modifier nature and MBA content. The ability to swelling of the samples filled by ZnO is higher than in the case of TiO2. This can be caused by the smaller size of TiO2 nanoparticles. At the same weight content of peroxidized filler this caused the increase of the quantity of cross-linking centers and as a result to the formation of hydrogel with higher curing degree. The results of the study physico-mechanical properties of obtained hydrogels with embedded TiO2 and ZnO NP are in a good agreement with the data obtained at the study of hydrogel swelling ability. So, with the increase of MBA concentration the tensile strength increased with simultaneous decrease of elongation at break that can be explained by the enhancement of curing density and rigidity of polymer hydrogel. At the same time, even in the case of MBA absence obtained hydrogels are characterized by rather high physico-mechanical properties.