Functional monomers and polymers, 74. Physico‐chemical study on the chitosan‐iodine complexes

Abstract

The adsorption of iodine on chitosan was studied by physico-chemical methods. The scanning electron micrograph measurements of chitosan-iodine adducts showed that iodine molecules were adsorbed uniformly on the chitosan film when the film was treated with aqueous iodine-potassium iodide solution. The thermogravimetric analysis of the adducts revealed that the loss in weight began at about 19O"C, and that iodine molecules were thus well-complexed with chitosan. It was also found that the IR spectra of the chitosan films showed the amide I and amide I1 bands shifted to lower frequencies due to the iodine adsorption. The X-ray diffractometry of these adducts was further carried out, and it was found that the iodine adsorbed chitosan showed no crystalline pattern, different from that of the original chitosan which showed crystallinity in some extent. The chitosan recovered after desorbing iodine by immersion in aqueous sodium thiosulfate solution was amorphous. ZUSAMMENFASSUNG :Die Adsorption von Jod an Chitosan wurde mit physikalisch-chemischen Methoden untersucht. Die Rasterelektronenmikroskopie von Chitosan-Jod-Addukten zeigte, daI3 Jodmolekille gleichmaig a n einen Chitosan-Film adsorbiert wurden, wenn der Film mit wal3riger Jod-Kaliumjodid-Lilsung behandelt wurde. Die thermogravimetrische Anaiyse der Addukte zeigte, d d der Gewichtsverlust bei 190°C begann und dal3 die Jodmolekille gut mit Chitosan komplexiert waren. Die IR-Spektren der Chitosan-Fihe zeigten die Amidbanden I und 11, die durch die Jodadsorption zu geringeren Frequenzen verschoben wurden. Rontgenbeugung an den Addukten zeigte, da8 das Chitosan, das Jod adsorbiert hatte, keine kristallinen Anteile aufwies.Im Gegensatz d a m zeigte das ursprilngliche Chitosan bis zu einem gewissen Grad Kristallinitgt. Das durch Eintauchen in eine w l h i g e Thiosulfatldsung vom Jod befreite Chitosan war amorph.

Molecular iodine/polymer complexes

“…As revealed by the 13 C NMR spectrum of the I 2 chitosan, the effect of heavy halogen (iodine) on the chemical shifts (δ) of the carbons of the glucosamine residue was not great; only the chemical shifts of C1, C3 and C4 were displaced to lower fields, but not significantly (Δδ≈0.1-0.2 ppm). This finding would suggest that the nitrogen atom was not involved in the binding of iodine as claimed elsewhere [98,99]. Another important facet of this study was that the coloring phenomenon is believed to be related primarily to I 3¯ ions and to the cylindrically shaped assembly of extended chitosan chains including iodine/iodide molecules.…”

Research on the preparation and characterization of chitosan grafted polyvinylpyrrolidone gel membrane with iodine

“…At the same time, the absorption peak at 1573 cm 21 was caused by the vibration of tertiary amino and AC@O symmetric contraction disappeared. The new absorption peak occurred at 1369 cm 21 which was due to CAH symmetry bending vibration of methyl, and the new absorption peak appeared at 1198 cm 21 was caused by the stretching vibration of CAO, CAN, and CAC. The strong absorption peak occurred at 903 cm 21 was the result of the plane bending vibration of CAH.…”

“…32 The absorption peak at 1418 cm 21 was due to the asymmetric bending vibration of NH 3 1 , the absorption peak at 1327 cm 21 was due to the CAH in-plane bending vibration, and the strong absorption peaks at 1130, 1060, and 713 cm 21 which were characteristic peaks of the saccharide structure. 30 Second, in comparison with the CS, the grafting of PVP on CS made the absorption peak at 3372 cm 21 , as the OH and NH stretching vibration of CS-PVP emulsion [ Figure 1(b) red line] moved to 3384 cm 21 . The absorption peak of aromatic carbon rings and C@O stretching vibration became stronger and the red line shifted to 1660 cm 21 .…”

“…The IR spectral absorption peak at 3282 cm 21 of CS-PVP-G-M [ Figure 5(a)] was due to the stretching vibration of OH and NH, and the intermolecular hydrogen bonds of the polysaccharide. The absorption peaks at 2923 cm 21 and 2856 cm 21 were the results of the stretching vibration of ACH 3 and ACH 2 A, respectively. The absorption peak at 1648 cm 21 was due to amide I of PVP and the polysaccharide, while the absorption peaks at 1562 cm 21 and 1313 cm 21 were caused by amide II and amide III, respectively.…”

“…A series of investigations on CS [13][14][15] and its derivatives [16][17][18][19] as drug delivery carrier have been performed, according to which CS has been found to play an important role in antibacterial drug delivery, as CS shows no obvious bacteriostatic effect when used as antimicrobial material. 20 Iodine has therefore been tried to be combined with CS to improve its antimicrobial activity of CS antimicrobial material, [21][22][23][24][25] but according to our experiment results and the conclusion of the combined forms between CS and iodine molecules made by Shigeno et al, 21 CS offers slight adsorption to iodine only. The absorption to iodine has been considered to be caused by n 2 d charge transfer between amino groups of CS and iodine molecules.…”