A influencia de modificacao quimica (por tratamento acido seguido de funcionalizacao com trietilenotetramina, TETA) sobre a superficie de nanotubos de carbono de paredes multiplas (MWCNT) foi estudada qualitativa e quantitativamente. A analise termogravimetrica (TGA) mostrou que, no caso do nanotubo funcionalizado com amina, 29% de perda de massa pode ser atribuida a -C(=O)TETA e grupos funcionais residuais que contem oxigenio. A espectroscopia de fotoeletrons excitados por raios X (XPS) foi utilizada para observar as funcoes aminadas e oxigenadas ligadas covalentemente a superficie do nanotubo. As imagens de microscopia de forca eletrica (EFM) indicaram que, a medida que se modifica a quimica superficial dos nanotubos em presenca de ar, estes mostram respostas diferentes em funcao do potencial da ponta. Deslocamentos nos sinais de fase de EFM decrescem quando se modifica a superficie dos tubos com grupos funcionais contendo oxigenio e amina. Em atmosfera seca e inerte de N 2 , as tres diferentes superficies mostraram a mesma resposta a EFM. Alem disso, o carater hidrofilico dos "buckypapers" cresceu na ordem MWCNT < MWCNT-aminado < MWCNT-oxidado. The influence of chemical modification by acid treatment followed by triethylenetetramine (TETA) functionalization on the surface of multi-walled carbon nanotubes (MWCNT) was evaluated, both qualitative and quantitatively. Thermogravimetric analysis (TGA) showed that, in the case of amine-functionalized nanotubes, 29% of mass loss can be attributed to -C(=O)TETA and residual oxygen-containing functional groups. X-ray photoelectron spectroscopy (XPS) was used to observe the oxygenated and aminated functions covalently linked to the nanotube surface. Electric force microscopy (EFM) images indicated that the nanotubes with diverse surface chemistry showed distinct responses to the tip potential in the presence of air. Shifts in EFM phase images decreased when the nanotube surface was modified with oxygen and amine-containing functional groups. In dry and inert N 2 atmosphere, however, the three different surfaces showed the same response to EFM. In addition, the hydrophilic character of the buckypapers increased in the order MWCNT < aminated-MWCNT < oxidized-MWCNT.