TEMPO氧化纤维素纳米纤丝对多壁碳纳米管分散性的影响

以竹粉为原料，采用2，2，6，6-四甲基哌啶-1-氧自由基（TEMPO）氧化法通过改变NaClO的添加量制备出不同羧基含量及形态的纤维素纳米纤丝（CNFs），并将制备的CNFs作为分散剂对多壁碳纳米管（MWCNTs）进行分散处理，得到不同分散浓度的CNFs/MWCNTs悬浮液，采用Beer-Lambert定律对MWCNTs的分散量进行测定，并采用原子力显微镜（AFM）、激光粒度分析仪（LPSA）等手段评价了不同羧基含量及形态的CNFs对MWCNTs的分散效果。结果表明:随着NaClO添加量的增加，CNFs的横截面直径逐渐变小，羧基含量逐渐增加，同时，CNFs对MWCNTs的分散量逐渐增大；当CNFs的羧基含量从0.635 mmol/g增加到1.646 mmol/g时，对MWCNTs的分散量从19%增加到39%；不同CNFs/MWCNTs悬浮液中的粒度分布系数（PDI）值均小于0.3，且不同悬浮液的Zeta电位绝对值均高于30 mV，表明不同羧基含量的CNFs均能对MWCNTs有较好的分散效果；同时，随着羧基含量的增加，CNFs对MWCNTs的分散效果越好，CNFs/MWCNTs复合薄膜的抗拉应力逐渐增大，而且电阻率逐渐降低，当CNFs羧基含量为1.646 mmol/L时，CNFs/MWCNTs复合薄膜抗拉应力达到了91 MPa，薄膜电阻率低至0.1460 Ωcm。 

Dispersion effect of TEMPO oxidized cellulose nanofibrils on multi-walled carbon nanotubes

In order to research the dispersion effect of the different cellulose nanofibrils (CNFs) on the untreated multi-walled carbon nanotubes (MWCNTs), the CNFs with different carboxyl content and form were isolated from bamboo powder by 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO) oxidation method with the different amount of NaClO added. The obtained different CNFs were used to disperse untreated MWCNTs as a dispersant, subsequently, the amount of MWCNTs dispersed in the different CNFs suspensions was measured with the Beer-Lambert law. The dispersion effect of the different CNFs on MWCNTs was evaluated by atomic force microscopy (AFM), laser particle size analyzer (LPSA) and so on. The results show that the carboxyl content of CNFs increases and the cross section diameter of CNFs decreases with the increase of NaClO added during TEMPO oxidizing. At the same time, the research also indicates that the dispersion amount of MWCNTs increases with the increase of the carboxyl content of CNFs. When the carboxyl content of CNFs increases from 0.635 mmol/g to 1.646 mmol/g, the percent of MWCNTs dispersed in the CNFs suspension increases from 19% to 39%. The different CNFs/MWCNTs suspensions show that the particle dispersion index (PDI) values of the particle size distribution are less than 0.3, and the absolute values of Zeta potential are higher than 30 mV, which proves that the MWCNTs could be well dispersed by the different CNFs. The CNFs/MWCNTs composite films display that the tensile stress increases and resistivity decreases with the increase of carboxyl group of the CNFs, when the carboxyl content of CNFs is 1.646 mmol/L, the tensile stress of CNFs/MWCNTs composite film can reach 91 MPa, and the resistivity is as low as 0.1460 Ωcm.