ABSTRACT
Objective To prepare chitosans of high degree of deacetylation with different molecular weights.Methods A series of chitosan samples of high degree of deacetylation were prepared by different approaches of hydrolysis from commercial chitosan in the presence of strong base.The obtained deacetylchitosans were then degraded into samples with medium or low molecular weight in the system of acetic acid and hydrogen peroxide.Their corresponding molecular weights were further determinied with Ubbelohde viscometer.Results Chitosans of high degree of deacetylation with different molecular weights were successfully prepared under the experiment conditions.Their characteristics were indicated and analysed by IR and 1H-NMR.Conclusion Chitosans of 90%~100% degree of deacetylation can be prepared by the intermittent approach of hydrolysis using 10mol?L-1 NaOH solution at 110℃.Chitosan samples with the viscosity-average molecular weigh between 10,000 ~100,000 Da can be prepared in the system of 0.35 mol?L-1 acetic acid and 0.45 mol?L-1 hydrogen hyperoxide.