Structural analysis of magnetic nanocomposites based on chitosan

KLOSTER, GIANINA A.; MURACA, DIEGO; MOSCOSO LONDOÑO, OSCAR; KNOBEL, MARCELO; MARCOVICH, NORMA E.; MOSIEWICKI, MIRNA A.

POLYMER TESTING

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2018 vol. 72 p. 202 - 213

0142-9418

This work investigates the structure and magnetic properties of chitosan based films with different contents ofmagnetic nanoparticles (MNPs) of around 10 nm as well as the effects of the addition of glycerol as plasticizer.Synthesized MNPs were dispersed in the chitosan film forming solution by ultrasonication and then compositefilms were obtained by casting. From the morphological analysis, a bimodal distribution of clusters was detected;the larger ones seem to be present mostly in the plasticized samples. Regarding the mechanical behavior of thesamples, for the non-plasticized samples the outstanding increase in modulus and strength with the increasingcontent of MNP was explained by a strong interfacial adhesion and very good particles dispersion into thechitosan matrix. This fact was also supported by the model applyed to the strength as a function of the volumefraction of MNP.Regarding magnetic properties, all nanocomposite films evidenced systems with particles of strong dipolarinteractions that lead to blocking and irreversibility temperatures close to room temperature (RT). Even thoughthe isothermal magnetization results showed that the particles in the nanocomposite films behave as superparamagneticat the highest analyzed temperature (RT). Langevin model as well as FESEM and SAXS analysissupported the hypothesis that the formation of aggregates with different features dominates the magnetic responsethrough collective behavior, mainly in the plasticized films.