纳米纤维素气凝胶的制备、表征及其性能研究

以纳米纤维素纤丝(NCFs)为原料,在四氯化锡的催化下与1,4-丁二醇二缩水甘油醚(BDGE)发生交联反应制备了多孔的纳米纤维素气凝胶,采用扫描电镜、傅里叶变换红外光谱仪、X射线衍射仪、热重分析仪、X射线光电子能谱和全自动比表面积及物理吸附分析仪,对制备的纳米纤维素气凝胶的微观形貌、化学结构、晶型结构、热稳定性、表面元素及比表面积进行了表征,考察了纳米纤维素气凝胶的密度、溶剂吸收、形状恢复以及重复使用性能。结果表明:NCFs与BDGE发生了交联反应,制备的纳米纤维素气凝胶具有连续的多孔网络结构,其仍保持原来的纤维素I型结构,初始分解温度在300℃以上,m(BDGE)∶m(NCFs)为2∶1时,制备的气凝胶密度为0.020 2 mg/cm3,比表面积为25.6 m2/g,吸水倍数为36.5 g/g。气凝胶在水中5 s能迅速恢复其原来形状,在DMSO中20 s能恢复形状的90%,气凝胶重复使用5次,吸水倍数仍高达30.4 g/g。

Preparation and Shape Recovery Property of the Nanocellulose Aerogels

The porous nanocellulose aerogels were obtained by the cross-linked reaction of 1, 4-butanediol diglycidyl ether (BDGE) and nanocellulose fibers (NCFs) with the catalyst of SnCl4. The morphological feature, chemical characterization, crystal structure, thermostability, element of nanocellulose aerogels and surface aera were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermo gravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analysis, respectively. The density, solvent absorption ability, shape recovery property and reusability of nanocellulose aerogels were investigated. The results showed that aerogels with continuous network pore structure still maintain the cellulose I crystalline structure and the aerogels started to degrade above 300 ℃. When the amount of BDGE was 2 times as much as the mass of NCFs, the density of aerogels was 0. 020 2 mg/cm3 , and aerogels could absorb water by 36. 5 g/g of their own weight. The recovery degree of aerogels immersed in water and DMSO could reach 90%. After reusing for 5 times, the water absorption ability of aegrogel was still up to 30. 4 g/g.