Application of scanning force microscopy in nanotube science

Abstract

Recent developments in the application of scanning force microscopy in nanotube science are reviewed. The non-destructive character of this technique allows the structural characterisation of (chemically modified) single-and multi-wall nanotubes deposited on substrates for further investigations such as electrical transport measurements. Furthermore, SFM is now an established tool for manipulation of nanotubes, which allows position control and determination of elastic constants such as the Young's modulus. Finally it is shown that very sharp and stable probes for scanning force microscopy can be made from nanotubes due to their excellent stability and aspect ratio.

Influence of Carboxylation on Structural and Mechanical Properties of Carbon Nanotubes: Composite Reinforcement and Toxicity Reduction Perspectives

“…This result confirms experimental observations ,,,, that carboxylation at some point leads to the deterioration of CNTs. Moreover, if the concentration of highly carboxylated CNTs in a composite matrix is sufficient, they will form large agglomerates, , thus making strong carboxylation useless for solving the bundling problem of pure CNTs. It should be emphasized that the results presented in this work perfectly describe those trends.…”

“…Nearly all theoretical studies of carboxylated CNTs ,− present a picture that is not consistent with experimental observations. ,,− Many people have falsely believed that the common oxidizing acid functionalization treatment yields CNTs with COOH groups added to the sidewall and that the carboxylation and grafting processes lead to similar property changes. Nevertheless, carboxylation is usually carried out by treating CNTs with oxidizing inorganic acids, such as HNO 3 and H 2 SO 4 , alone or in combination with peroxide. ,,,− ,, The carbon atom in the COOH linkage is one of the CNT backbone carbons. This requires one of the sidewall carbon atoms to have three new bonds to oxygen atoms, leaving only one bond to another sidewall carbon, which means that a surface group and a vacancy in the CNT wall are present simultaneously.…”

“…Carboxylation is used for nanotube purification and as a first step of target functionalization. 9,10 COOH groups allow for the coupling of other molecules through the creation of amide and ester bonds. This enables the formation of building blocks for various applications, including chemical, biological, and medical sensing; drug delivery; and catalysis.…”

“…Nevertheless, carboxylation is usually carried out by treating CNTs with oxidizing inorganic acids, such as HNO 3 and H 2 SO 4 , alone or in combination with peroxide. 9,16,19,[26][27][28]31,32 The carbon atom in the COOH linkage is one of the CNT backbone carbons. This requires one of the sidewall carbon atoms to have three new bonds to oxygen atoms, leaving only one bond to another sidewall carbon, which means that a surface group and a vacancy in the CNT wall are present simultaneously.…”

“…Among different types of chemical modifications, carboxylation is the most common and effective procedure. , It is an important process that is applied routinely for several purposes, not only for increasing the dispersibility of nanotubes in composites. Carboxylation is used for nanotube purification and as a first step of target functionalization. , COOH groups allow for the coupling of other molecules through the creation of amide and ester bonds. This enables the formation of building blocks for various applications, including chemical, biological, and medical sensing; drug delivery; and catalysis. − Carboxylated CNTs have been successfully used for water filtration, anticancer therapy, and the removal and inactivation of viruses and bacteria .…”