氧化纤维素的制备及其对碳纳米管的分散效果

Preparation of Oxidized Cellulose Being Used as Dispersant for Carbon Nanotubes

以针叶木溶解浆纤维素作为原料,经HNO_3/H_3PO_4/NaNO_2氧化体系选择性氧化后,制备了氧化纤维素(OC)。考察时间、温度及NaNO_2用量对OC的得率及羧基含量的影响,利用傅里叶红外光谱(FT-IR)、X射线衍射仪(XRD)和热重分析仪(TGA)对OC结构和性能进行表征。采用超声波法得到OC水溶液纳米粒子,透射电子显微镜(TEM)和动态光散射(DLS)结果表明:OC在水溶液中可形成均一分散的球形粒子,粒径位于纳米尺寸范围内(30~80 nm)。OC的较优制备工艺条件为:温度为50℃,NaNO_2用量为1.4%,时间为12 h。FT-IR和XRD分析表明:OC分子链中成功引入了羧基官能团,氧化过程中纤维素结晶区和无定形区均受到破坏。相比水和纤维素而言,OC水溶液纳米粒子对碳纳米管(CNT)具有优异的分散效果,其剩余浊度为82.5 NTU,分散效果持续稳定30天以上。

The oxidized cellulose（ OC） was prepared through selective oxidation of softwood dissolving pulp cellulose by HNO3/H3PO4/NaNO2 oxidant. The effects of oxidizing conditions,e.g.,oxidizing time,temperature and dosages of NaNO2 on the yields and carboxyl groups contents of OC were studied. The structures and properties of OC samples were characterized by Fourier transform infrared spectroscopy（ FT-IR）,X-ray diffraction（ XRD） and thermogravimetric analysis（ TGA） respectively. The nanoparticle solution was prepared by dispersing the OC sample in aqueous solution under ultrasound wave. The sizes and morphologies of particles were characterized by dynamic light scattering（ DLS） and transmission electron microscopy（ TEM）. The results showed that the nanoparticles were spherical in shape with monodisperse,and the sizes of micelles were in the range of30 nm to 80 nm. The optimum conditions of OC preoaration were as the followings： reaction temperature 50 ℃,NaNO2 dosage 1.4 % and reaction for 12 h. Compared with water and cellulose,the OC nanoparticle was an excellent aqueous dispersant for multi-walled carbon nanotube（ CNT）.