中文摘要：

先用甲醛-甲酸法（eschweiler-clarke反应）合成N,N-二甲基壳聚糖（DMC）,再与溴代烷进行Hoffman烷基化反应制备了N-十二烷基-N,N-二甲基壳聚糖季铵盐（DODMC）和N-十六烷基-N,N-二甲基壳聚糖季铵盐（HDMC）,用FT-IR、1 H NMR、EA、TG等对产物进行表征。抗菌实验结果表明所合成产物具有较好的抗菌活性,对革兰氏阳性菌S.aureus的抗菌活性优于革兰氏阴性菌E.coli,抗菌活性随着烷基链长度的增加而增强;产物在pH值=5.5比在pH值=7.2条件下表现出更好的抗菌活性;在碱性及中性条件下,HDMC的抗菌活性随着季铵化度的提高而提高,而在酸性条件下抗菌活性则随着季铵化度提高而降低。

英文摘要：

A formic acid-formaldehyde methylation（eschweiler-clarke reaction） was used to synthesize N,N-dimethylated chitosan（DMC） at first,then DMC and bromoalkane was used to synthesize N-dodecyl-N,N-dimethyl chitosan（DODMC） and N-hexadecyl-N,N-dimethyl chitosan（HDMC） according to Hoffman alkylation.The obtained chitosan derivatives were characterized by FT-IR,1H NMR,EA,TG methods,respectively.The derivatives showed good antibacterial activity,and they exhibited stronger antibacterial activity against S.aureus than against E.coli.The antibacterial activity of chitosan derivatives was increased as the length of alkyl increased.The antibacterial activity of chitosan derivatives was stronger under pH 5.5 than under pH 7.2;the results suggested that in basic or neutral,the antibacterial activity of HDMC was increased as the degree of quaternized increased;but in acid,the antibacterial activity of HDMC was declined as the degree of quaternized increased.