Ⅱ晶型纤维素纳米晶的一步绿色制备

One-step Green Preparation of Cellulose Ⅱ Nanocrystals

Ⅱ晶型纤维素纳米晶(CNC-Ⅱ)是纤维素纳米晶多种晶型中热力学最为稳定的晶型结构,有望满足高温环境的使用需求。针对目前CNC-Ⅱ制备方法繁琐复杂,所使用试剂昂贵或有毒等问题,利用高铁酸钾在碱性环境中的强氧化性,开发了一种高铁酸钾氧化水解棉纸浆纤维素一步绿色制备CNC-Ⅱ的方法。通过研究碱浓度在制备过程中对晶型转变和产率的影响,确定了最佳碱浓度为5 mol·L^(-1)。扫描电镜表征结果表明:CNC-Ⅱ为粒状形貌;红外表征结果表明:CNC-Ⅱ在3492和3445 cm^(-1)等位置具有Ⅱ晶型纤维素特征峰;热重分析表征结果表明:CNC-Ⅱ的热稳定远高于普通酸解法的Ⅰ晶型CNC-OSO_(3)^(-)。

CelluloseⅡnanocrystal(CNC-Ⅱ)is the most thermodynamically stable crystalline structure of cellulose nanocrystal in various crystal forms,which is expected to meet the needs of high temperature environment.In view of the complicated preparation methods of CNC-Ⅱ,expensive or toxic reagents and other problems,this paper developed a one-step green preparation method of CNC-Ⅱby using potassium ferrate to oxidize cotton pulp cellulose,which has strong oxidability in alkaline environment.By studying the effect of alkali concentration on crystal transformation and yield,the optimum alkali concentration was determined to be 5 mol·L^(-1).SEM characterization results showed that CNC-Ⅱwas granular morphology.FT-IR results showed that the characteristic peak of CNC-Ⅱappeared at 3492 and 3445 cm^(-1).TG characterization results showed that the thermal stability of CNC-Ⅱwas much higher than that of polymorphⅠCNC-OSO_(3)^(-)by common acid hydrolysis method.