Abstract: In this project，O-methyl free N,N,N-trimethyl chitosan (TMC) was synthesized in two steps，then N,N,N-trimethyl O-octyl chitosan(TMOC) was prepared with phase transfer catalysts. The obtained chitosan derivatives were characterized by FTIR，1H NMR，EA and TG methods，respectively. The results reveal that the antibacterial activity of TMOC is stronger under pH 5.5 than that under pH 7.2；TMOC exhibits stronger antibacterial activity against S. aureus than against E. coli. Without compromise on the water-solubility，O-alkylation can improve the antibacterial activity of TMC. The antibacterial activity of TMOC increased as the degree of O-alkylation increased. The results can provide a reference for the modification and the preparation of chitosan antibacterial agents.

Key words: chitosan, quaternary ammonium, alkylation, antibacterial activity

摘要： 先用两步法合成了无O-甲基化 N,N,N-三甲基壳聚糖季铵盐（TMC），再通过相转移催化合成了N,N,N-三甲基O-辛基壳聚糖季铵盐（TMOC），用 FTIR、1H NMR、EA、TG 等方法对产物进行表征，并研究其抗菌性能。结果表明，TMOC在pH值为5.5的抗菌活性优于pH值为7.2的抗菌活性；TMOC对革兰阳性菌S. aureus的抗菌活性比革兰阴性菌E. coli强。在不影响水溶性的前提下，O-烷基化改性能有效提高壳聚糖季铵盐的抗菌活性，并且抗菌活性随着O-烷基化度的提高而提高。研究结果为壳聚糖基抗菌剂的改性和制备提供了依据。

关键词: 壳聚糖, 季铵盐, 烷基化, 抗菌活性