1 research outputs found
Superparamagnetic Nanocomposites Based on the Dispersion of Oleic Acid-Stabilized Magnetite Nanoparticles in a Diglycidylether of Bisphenol A-Based Epoxy Matrix: Magnetic Hyperthermia and Shape Memory
Superparamagnetic nanocomposites were obtained by dispersion
of
oleic acid (OA)-coated magnetite NPs in an epoxy system based on diglycidylether
of bisphenol A (DGEBA) modified with OA. Dispersion of conventional
oleic acid-stabilized magnetite NPs in a typical epoxy matrix is not
possible due to the dissimilar chemical structures of the organic
coating and the reactive solvent. However, by modification of a DGEBA-based
epoxy with 20 wt % OA, we obtained a suitable reactive solvent to
disperse up to at least 8 wt % of OA-stabilized magnetite NPs. A tertiary
amine was used to catalyze the epoxy–acid reaction and initiate
the homopolymerization of the epoxy excess. Both reactions occurred
practically in series, first the epoxy–acid and then the epoxy
homopolymerization. It was necessary to complete the first reaction
to attain a very good dispersion of magnetite NPs in the reactive
solvent previous to the occurrence of the final reaction. Magnetization
curves and TEM images revealed a uniform dispersion of individual
nanoparticles in the cross-linked epoxy. A sample containing 8 wt
% OA-coated magnetite NPs exhibited a temperature increase of 25 °C
at its surface when exposed to an alternating magnetic field. The
temperature increase was enough to induce the shape memory effect
of the nanocomposite