采用了1种新的三成分氧化体系(浓硫酸/高锰酸钾/过氧化氢)对多壁碳纳米表面进行羧基化改性，并对比分析了反应过程中采用超声辅助的方式对碳纳米管羧基化程度的影响.红外和X射线光谱分析结果证实了改性多壁碳纳米管表面引入了含氧官能团如—COOH、—OH、—C??O 等，且采用超声辅助的氧化体系氧化效果更好，所改性的羧基化多壁碳纳米管中氧含量高达20．98％(原子分数)，明显高于文献中及市场上的羧基化多壁碳纳米管氧元素含量；通过对比改性前、后多壁碳纳米管在乙醇水溶液的分散性，结果表明采用本研究中的氧化体系进行改性的多壁碳纳米管的分散性有明显的提高；场发射扫描电镜观察改性后多壁碳纳米管的表面形貌进一步表明改性前、后的多壁碳纳米管结构长度未发生明显的缩短，而且羧基化过程中采用超声辅助获得的多壁碳纳米管未发生明显的团聚现象.
Here,carboxylation multiwalled carbon nanotubes (MWCNTs-COOH)were synthesized via a novel mild oxidation approach assisted by ultrasonication.A mild oxidation system with three oxidation agents as con-centrated sulphuric acid,potassium permanganate,and hydrogen peroxide were chosen.In comparing to nonul-trasonic process,the effect of ultrasound-assisted process on the carboxyl content of MWCNTs-COOH was dis-cussed.Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that oxygen-containing functional groups such as —COOH,—OH,—C??O were successfully attached on the surface of nanotubes.The results verified that the ultrasound-assisted oxidation process are much more effective than that without using ultrasonication,a higher oxygen content as 20.98at% in resulted MWCNTs-COOH were esti-mated,which exceeds the content of as-received carboxylated MWCNTs.A better dispersion of MWCNTs-COOH in ethanol was expected.Finally,field-emission scanning electron microscope (FESEM)images revealed that the length of MWCNTs-COOH was not shortened during the mild oxidation approach and the agglomera-tion was significantly reduced in the ultrasound-assisted oxidation process.
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