C6位氧化细菌纤维素的制备及结构表征

Preparation and Structure Characterization of C6-Oxidated Bacterial Cellulose

为了改善细菌纤维素的生物降解性,采用2,2,6,6-四甲基-1-哌啶酮(TEMPO)/Na Br/Na Cl O体系对细菌纤维素进行氧化,探讨了Na Cl O和TEMPO用量及反应时间对反应的影响,利用电导滴定、红外光谱、13C-核磁共振、X射线衍射和透射电子显微镜对固体产物进行了表征。结果显示,细菌纤维素取1 g,0.6 mol/L Na Cl O 8 m L,TEMPO 0.016 g,Na Br0.1 g,反应8 h可以获得羧基含量较高的氧化细菌纤维素(羧基含量为1.04 mol/kg)。红外光谱和13C-核磁共振波谱共同证明细菌纤维素C6位伯醇羟基被选择性催化氧化成了羧基,X射线衍射结果表明氧化后细菌纤维素的结晶结构没有发生明显改变,TEM结果显示氧化后细菌纤维素的纳米网状结构得到保留。利用TEMPO/Na Br/Na Cl O体系可以获得氧化度较高的微观结构无损伤的氧化型细菌纤维素。

To improve its biodegradability,2,2,6,6-tetramethyl-1-piperidinyloxy( TEMPO)-mediated oxidation of bacterial cellulose( BC) was studied with change of the amount of Na Cl O,TEMPO and the oxidation time. The product oxidated bacterial cellulose( OBC) was characterized by conductometric titration,FT-IR,solid-state13C-NMR,XRD and TEM. The results show that,OBC with high carboxyl content( 1. 04 mol / kg) can be prepared under the following conditions: 1 g BC,8 m L 0. 6 mol / L Na Cl O,0. 016 g TEMPO,0. 1 g Na Br and action time of 8 h; FT-IR and13C-NMR together prove that the C6 primary hydroxyl group was selectively oxidized into carboxylic group; the XRD analysis indicates that the crystalline texture of OBC has no significant variation compared with BC; the TEM result suggest that the nano network structure of bacterial cellulose was retained after oxidation. Using the TEMPO / Na Br / Na Cl O oxidative system,obtained the OBC with high carboxyl content and scatheless microstructure.