| 摘要 |
A carboxymethyl substituted chitosan having a degree of substitution of carboxymethyl groups per glucosamine monomer unit in the chitosan of less than l.0, characterised in that some of the carboxymethyl groups are substituted on hydroxyl oxygen atoms of the glucosamine monomer units, of the chitosan and the other carboxymethyl groups are substituted as nitrogen atoms of the glucosamine monomer units of the chitosan. The invention also includes a method of producing the aforesaid carboxymethyl cellulose substituted chitosan characterised by forming a slurry of chitosan in a selected liquid medium, adding strong aqueous caustic soda to said slurry to provide 3 to 8 mol NaOH per mol of glucosamine chitosan monomer units of one and steeping for 0.l to l.0 hours, adding monochloreacetic acid to the steeped slurry in an amount to provide l mol of acid per l.8 to 2.2 mol NaOH, heating to a reaction temperature of substantially 40 DEG C to substantially 70 DEG C and maintaining a temperature in that range whilst stirring for a period of 2-l2 hours to effect substitution of carboxymethyl groups both in hydroxyl groups and in nitrogen atoms of the glucosamine monomer units adding enough water for pH measurement and adding glacial acetic acid to bring the pH of the slurry to substantially 7 and recovering the aforementioned carboxymethyl substituted chitosan from the slurry. The invention also includes films produced from the aforesaid substituted chitosan and substrates coated with such films. |
