Thermal stability of magnetic nanoparticles coated by blends of modified chitosan and poly(quaternary ammonium) salt

Magnetite nanoparticles (Fe3O4 NPs) coated by modified chitosan (m-CS) rich of amino groups and its mixture with poly[N-benzyl-2-(methacryloxy)-N,N-dimethylethanaminium bromide] (PQ) with various mass ratios were prepared by co-precipitation method. The thermal stability of magnetic materials has been investigated by thermogravimetric analysis (TG/DTG/DTA) in air and nitrogen atmosphere. It was found that magnetic NPs coated by polymer blend were characterized by lower thermal stability than protected only by alone CS or m-CS. Magnetite NPs enhance thermooxidative degradation of polymers, however, the stable surface layer, formed from polymer degradation products, efficiently protects the magnetite transformation at higher temperatures. The content of magnetite in obtained systems has been also determined from TG curves.