Magnetic nanocomposites based on shape memory polyurethanes

Abstract

Shape-memory composites based on a commercial segmented polyurethane and magnetite (Fe 3 O 4) nanoparticles (MNPs) were prepared by a simple suspension casting method. The average sizes of individual magnetic particles/clusters were determined by TEM microscopy and corroborated from SAXS patterns. The magnetization properties of selected samples were evaluated using zero field cooling/field cooling (ZFC/FC) measurements and magnetization loops obtained at different temperatures. The results showed that magnetization at high field (20 kOe) and coercitivity measured at 5 K increase with magnetite content and that all the composite films exhibit superparamagnetic behavior at 300 K. The specific absorption rate (SAR) of the nanocomposites was calculated by experimentally determining both the specific heat capacity and the heating rate of the films exposed to an alternant magnetic field. All nanocomposites were able to increase their temperature when exposed to an alternant magnetic field, although the final temperature reached resulted dependent of the MNPs concentration. What is more, a fast and almost complete recovery of the original shape of the nanocomposites containing more than 3 nominal wt.% MNP was obtained by this remote activation applied to the previously deformed samples.

Magnetic Fe3O4 based layered double hydroxides (LDHs) nanocomposites (Fe3O4/LDHs): recent review of progress in synthesis, properties and applications

“…1a coercivity (HC), remanence magnetization (Mr), the saturation magnetization (MS) can be obtained from the hysteresis loops. The backward and forward magnetization curves overlap completely [62,63]. Many synthetic techniques have been developed to prepare magnetic Fe 3 O 4 MNPs such as sol-gel [64], hydro thermal/solvothermal [65], sonochemical [66], micro-emulsion [67] and co-precipitation methods [68,69].…”

Oil Spill Sorber Based on Extrinsically Magnetizable Porous Geopolymer

“…The X-ray diffraction analyses were carried out to identify the crystalline peaks related to geopolymers’ formation with magnetic particles and the modification of the magnetic particles with SiO 2 . Thus, it was possible to identify peaks at 17° angles in the composites, 27.5°, 37°, 41°, and 47° referring to the Sodalite phase and the 24° and 30° peaks of quartz, these being the main formation phases of geopolymers [ 31 ]; furthermore, the peaks centered at 35° and 51° identified the presence of magnetite inserted in the geopolymer matrix shows the Figure 3 A(a) [ 32 , 33 , 34 , 35 , 36 ].…”

Polymeric Nanocomposites for Environmental and Industrial Applications

“…Soto et al fabricated polyurethane/Fe 3 O 4 nanocomposites and also investigated the influence of the Fe 3 O 4 content on shape recovery and heat release when these nanocomposites were exposed to AMF. It was revealed that the time taken to achieve shape recovery was directly correlated with the Fe 3 O 4 content [65]. In another work, nanocomposites comprising Kappa carrageenan-g-poly(acrylic acid)/SPION were observed to be effective as in vitro antibacterial agents with the drug efficiency of 105 ± 8 µg/mg exhibited by the drug carrier [75].…”

“…Magnetic nanoparticles (MNPs) exhibit magnetic induction heating, which facilitates their application in biomedical fields, including targeted drug delivery and elastomer fabrication [65][66][67]. The performance of magnetic induction heating relies mainly on the properties of the MNPs and the applied magnetic field conditions.…”