The Surface Functionalization of Multiwalled Carbon Nanotubes

The aim of this paper is to develop methods of oxidation of multiwalled carbon nanotubes (MWCNTs) and determine their functional dependence on oxidation conditions. Based on initial MWCNTs we synthesize three series of samples oxidized under different conditions: by concentrated hydrogen peroxide mixed with sulfuric acid under standard conditions, by concentrated hydrogen peroxide mixed with sulfuric acid during boiling, by concentrated nitrate acid at temperatures of 50, 75 and 100 оC. Functional groups on the MWCNTs surface are qualitatively and quantitatively characterized by Boehm titration method. We discover that treatment of multiwalled carbon nanotubes with concentrated hydrogen peroxide in the sulfuric acid presence under standard conditions for 2–27 hours leads to formation of mainly phenolic groups and a small number of lactones on their surface. However, it does not lead to formation of carboxylic acid groups. Moreover, smaller levels of oxidation can be reached at MWCNTs oxidation by hydrogen peroxide in a mixture of sulfuric acid under reflux for 1–60 minutes than at the same mixture treatment at room temperature. The increase in temperature oxidation contributes to formation of carboxyl groups and does not contribute to formation of lactone groups. The content of phenolic groups prevails in both series of samples.

Publication year: 
С. 140—145. Іл. 10. Табл. 1. Бібліогр.: 21 назва.

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