INFLUENCE OF THE SOLID-LIQUID PHASE TRANSITION ON THE MAGNETIZATION OF FERROFLUIDS AND WET FERROGELS

GUSTAVO ALBERTO PASQUEVICH; PEDRO MENDOZA ZÉLIS; LORENA ARCINIEGAS; ELISA DE SOUSA; MARCELA FERNÁNDEZ VAN RAAP; JIMENA GONZÁLEZ; CRISTINA HOPPE; VERA ALVAREZ; FRANCISCO HOMERO SÁNCHEZ

Buenos Aires

Congreso; X LAW3M (Tenth Latin American Workshop on Magnetism, Magnetic Materials and their Applications).; 2013

Asociación Física Argentina

Developing magnetic nanomaterials for biomedical purposes is a highly relevant scientic and technological goal. Ferrofuids and ferrogels based on iron oxide nanoparticles (NPs) had been produced for their use in magnetofection and magnetic hyperthermia therapies, in the case of ferrouids, and drug delivery in the case of ferrogels. In this work the solid-liquid phase transition eects on magnetization have been studied in systems composed of magnetic NPs in contact with a liquid medium. Samples used are aqueous ferrofuids of iron oxide NPs of about 10 nm, synthesized by chemical coprecipitation. These NPs are functionalized with citric acid. Ferrogels are composed of iron oxide NPs, with sizes between 6-8 nm, dispersed in a polyvinyl alcohol (PVA) hydrogel synthetized by the freezing-thawing technique. M vs T cycles (cooling-warming) were recorded between 223 and 300 K under constant eld (from 3.97e3 to 1.59e6 A/m) by SQUID magnetometry. All studied systems presented abrupt changes in magnetization around defined temperatures, which do not depend on applied field or temperature variation rate, although they depend on the variation direction. In the cooling process an abrupt change in magnetization followed by a relaxation process was found. For ferrofuids this temperature is about 254 K and for ferrogels, about 265 K. In the warming process the transition is smoother and in both systems occurs at around 273 K.