IN-SITU SYNTHESIS OF FERRITES IN IONIC AND NEUTRAL CELLULOSE GELS

The filaments of a tyrecord rayon were modified by two methods to enha nce the degree of swelling of the material: (1) carboxyl and sulfonic acid substituents were introduced into the rayon and (2) the filaments were swollen in sodium hydroxide. The water-swollen filaments were re ndered magnetic by in situ synthesis of ferrites and the resulting mag netic filaments were characterized by transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). Two other non-ionic, h ighly swollen cellulose gels were used as matrices for in situ synthes is of ferrites: a never-dried, wet-spun model cellulose filament and a never-dried bacterial cellulose membrane. TEM micrographs of thin cro ss-sections of the magnetic gels showed that the nanometre-sized ferri tes were uniformly distributed whereas the treated rayon filaments had ferrites predominantly at the filament surface. All the materials wer e superparamagnetic as determined by VSM. However, a ferrimagnetic com ponent was detected after several reaction cycles for the bacterial ce llulose membrane by Mossbauer spectroscopy.