TEMPO及其衍生物制备纳米纤维素及其智能调节方法的研究进展

2,2,6,6-四甲基哌啶氧自由基(TEMPO)共氧化剂体系被广泛应用于选择性氧化纤维素的C6位伯醇羟基。在氧化过程中,纤维素的聚合度大幅度降低,因此被应用于制备纳米纤维素。随着TEMPO/NaClO/NaBr氧化技术的发展成熟,TEMPO/NaClO/NaClO2和4-乙酰胺基-TEMPO/NaClO/NaClO2体系都得到了广泛关注。随着研究的深入,TEMPO及其衍生物氧化体系已经成为一种高效且全pH范围适用的选择性氧化体系。TEMPO/NaClO/NaBr氧化体系在pH范围9～11活性最高,TEMPO/NaClO/NaClO2体系能够应用于pH中性的条件下,4-乙酰胺基-TEMPO/NaClO/NaClO2体系一般的pH使用范围为3.5～6.8。传统的TEMPO氧化过程需要持续手动控制pH恒定,操作繁琐,可控性差,应用缓冲溶液可控制TEMPO氧化过程中pH在一定范围内恒定,从而实现了TEMPO氧化体系的智能控制。文章综述了TEMPO及其衍生物制备纳米纤维素及其智能调节方法的研究进展。

Research Progress of Automatic Control Method and Nanocellulose Prepared by TEMPO and TEMPO-Analogous Mediated Oxidation

2,2,6,6-tetramethylpiperidine-l-oxyl radical （TEMPO）-mediated oxidation is widely used to effectively convert C6 primary hydroxyl groups to carboxyl groups. TEMPO-mediatedoxidation is widely used to prepared nanocelluse because degree of polymerization of cellulose would be decreased obviously during the oxidation process. Along with the development ofTEMPO/NaClO/NaBr oxidation technology, TEMPO/NaClO/NaClO2 and 4-acetamido-TEMPO/ NaClO/NaClO2 had attracted wide attention. With the development of TEMPO and TEMPO-analogous oxidation system, TEMPO-mediated oxidation system became efficient and applicable for the whole pH valve. TEMPO/NaClO/NaBr oxidation system can be used at pH 9～11,TEMPO/NaClO/NaClO2 was efficient at pH 7, and the optimal pH value of 4-acetamido- TEMPO/NaClO/NaClO2 was at pH 3.5～6.8. In traditional method, the control ofpH at a constantlevel throughout the oxidation process is a complicated task. It was reported that the applicability of the carbonate buffer system and the borax buffer system with various dropping rate of sodiumhypochlorite solution was considered, automatic control of TEMPO-mediated oxidation was came true. This paper was mainly discussed the research process of automatic control method andnanocellulose prepared by TEMPO-ananlogous mediated oxidation.