Study On The Technology Of Magnetic Chitosan Microsphere

Magnetic polymer microspheres which have outstanding environmental protectionand high controllability of their shapes and particle size are highly valued. Among them,magnetic chitosan microspheres are characteristic of non-toxic, environmentally friendlyand easy biodegradation, and have been widely applied in medical and other fields. Theaim of the paper is to study the preparation and characterization of the magnetic chitosanmicrospheres with two different methods. It covers the following aspects:1) Preparation of Fe3O4nano-particles by chemical co-precipitation method andultrasonic-assistedFe3O4nano-particles were prepared by chemical co-precipitation method assisted withultrasonic waves, with FeCl3·6H2O and FeCl2·4H2O as Fe resources and NH3·H2O asprecipitant. The results of the single factor and orthogonal experiment optimization showsthat best preparation conditions for magnetic particles is ultrasonic environment,n(Fe2+):n(Fe3+)=1:1.75, pH=9~11and reaction temperature50℃. Compared withmechenical stirring, the distribution of particles size under ultrasonic-assisted is narrowerand its dispersity is better by ultrasonic method, and nano-Fe3O4does not exhibit obviousreunion phenomenon.2) Preparation of Fe3O4nano-particles by co-precipitation method with ionic liquidsas solventsCompared with traditional molecular solvents (water and organic solvent), thecharacteristics of ionic liquids was frequently ignored. In this paper, we try to use cholinechloride/urea as the deep eutectic solvents (DES) and KOH as precipitant for Fe3O4nano-particles preparation. Compared to the ultrasonic assisted co-precipitation method,the average particle size of the obtained Fe3O4nano-particles can be up to tens ofnanometers and reunion phenomenon is decreased considerably. DES can also recycledand reused, which reduces the production cost greatly.3) Preparation of chitosan magnetic microspheres using emulsion cross-linkingmethodThe magnetic chitosan microspheres were prepared with the aboved-made Fe3O4andchitosan by chemical co-transformation and emulsion cross-linking method, respectively.The structure and morphology of the magnetic chitosan microspheres are characterized byFI-IR, SEM, TEM, TGA and XRD. The results indicate that Fe3O4is successfully wrapped in the interior of the microspheres. Comparison of chemical co-transformation andemulsion cross-linking method indicates that emulsion cross-linking method is simple andthe dispersity and magnetic responsiveness of the microspheres is obviously better thanthat of the chemical co-transformation.