SYNTHESIS AND CHARACTERIZATION OF MAGNETIC FILMS BASED ON MAGNETITE NANOPARTICLES IN A KAPPA-CARRAGEENAN BIOPOLYMER MATRIX

• Main Author: Artha Febriyanti Turnip, Maria
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86958
• Institution: Institut Teknologi Bandung

Magnetic films were fabricated using the solution casting method, with kappacarrageenan as the matrix, glycerol as the plasticizer, and magnetite nanoparticles (Fe?O? NPs) as the magnetic material. Fe?O? NPs were synthesized using the coprecipitation method with iron sand as the precursor. TEM imaging revealed that Fe?O? NPs formed agglomerates due to their magnetic properties. The nanoparticle surface was modified with trisodium citrate. A comparison of the XRD patterns of Fe?O? NPs and trisodium citrate-modified Fe?O? NPs (Fe?O? NP-TS) confirmed that surface modification did not alter the crystal structure. The presence of citrate on the nanoparticle surface was observed in the FTIR spectrum through asymmetric and symmetric carboxylate stretching. TEM images of Fe?O? NP-TS displayed a more uniform shape with continued agglomeration. The resulting kappacarrageenan-glycerol matrix was flexible and semi-transparent. The carboxylate groups made Fe?O? NPs hydrophilic, enabling easier dispersion within the kappacarrageenan matrix. The magnetic film appeared black-brown and remained flexible. The kappa-carrageenan-glycerol matrix showed an amorphous structure. The XRD pattern of the magnetic film matched those of the matrix and Fe?O? NPTS. The XRD intensity of the magnetic film increased as more Fe?O? NP-TS was added. SEM images of the magnetic film confirmed the presence of Fe?O? NP-TS in agglomerates dispersed throughout the matrix. The film’s surface was uneven due to the non-uniform distribution of Fe?O? NP-TS. EDS analysis further confirmed the presence of Fe?O? NP-TS through the detection of iron (Fe) alongside matrix elements. Optical properties were analyzed using UV-Vis spectroscopy. The magnetic film absorbed light in the UV range, suggesting potential applications for UV protection. The magnetization versus field (MH) curve indicated that the magnetic film exhibited soft ferromagnetic behavior with a low coercive field. Increasing the Fe?O? NP-TS content in the film enhanced its magnetization. The film's electrical properties were measured using impedance spectroscopy with variations in the setup, and the results were presented as Cole-Cole plots. The impedance curve included two components: the tail part from sample-electrode contact and the semicircle part corresponding to the sample. Under ambient conditions, the impedance curve decreased over time, making measurements under varying magnetic fields can not be observed. The presence of hygroscopic materials, such as kappa-carrageenan and glycerol, emphasized the need for an optimized measurement setup. Additionally, proper electrode selection was critical to prevent interaction when in contact with the surface of film. Impedance spectra measurements were subsequently performed under vacuum conditions using Cu-Sn electrodes and gold (Au)-deposited magnetic films. Under this setup, the resistance (R) component of the magnetic film dominated over the constant phase element (Q), indicating that the applied electric field tended to dissipate rather than store energy.