Carbon Nanotubes (CNTs) from Synthesis to Functionalized (CNTs) Using Conventional and New Chemical Approaches

Table 4

Main parameters for amidation type functionalization of CNTs for multiple applications.

Author	CNT type	Functionalization agent		Catalyst	Properties	Application	Ref
Antolín-Cerón et al.	CNT	(1) H2SO4:HNO3; (2) Dimethylformamide; (3) 4 aminobenzoic acid	60°C; 80°C; 130°C	—	f-CNTs present low thermal stability due to the presence organic substituent	Nanocomposites (reinforcement agent for polyurethane (PU))	[217]
Wang et al.	MWCNT	N, N0-Dicyclohexylcarbodiimide (DCC) and p-phenylenediamine	50°C	—	Diameter of carbon nanotubes is ~20 nm	Water-dispersible electrochormic nanocomposites	[218]
Bahramnia et al.	MWCNT	3-(Triethoxy silyl) propyl amine (TESPA) with different concentration 150, 75, and 25 wt.%	80°C	TEA	(i) Presence of amide in functionalized MWCNTs; (ii) Modification of MWCNTs with respect to the pristine; MWCNTs morphology; (iii) The measurable mean diameter sizes of 25 wt.%, 75 wt.%, and 150 wt.% TESPA MWCNTs were 41.6, 49.2, and 80.38 nm	The effect of 3-(triethoxy silyl) propyl amine concentration on surface modification of multiwall carbon nanotubes	[219]
Blaskievicz et al.	CNT	1-(3-Aminopropyl)imidazole	Room temperature	—	After reduction of functionalized CNT, the carbons attached to oxygenated groups did not return to the sp^2 hybridization or restore a typical hexagonal graphitic structure; No variation in the interlayer distance	Nanocatalysts derived from magnetic carbon nanotubes	[220]
Janudin et al.	CNT	Dodecylamine	80°C	H2SO4	Diameter distribution of CNT-amide was slightly decreased which was in the range of 10 to 109 nm, and the mean diameter was 32.16 nm with a standard deviation of 17.01; The functionalized CNTs are better aligned and denser because of the insertion of a new functional group	Effect of functionalized carbon nanotubes in the detection of benzene at room temperature	[221]
Anandhi and Benial	MWCNT	L-Alanine	Room temperature	—	(i) Rough surface morphology because of the attachment of the alanine; (ii) Larger diameter for the functionalized MWCNTs (mean diameter 84.80 nm); (iii) No agglomeration for functionalized MWCNTs; (iv) Helix form of structure of functionalized MWCNTs	Biomedical	[222]
Gao et al.	MWCNT-COOH	Ethylenediamine (EDA)	—	—	(i) The boundary of MWCNTs-A was blurry, and thin films were adhered to the tubes; (ii) Surface of MWCNTs-A is rougher than that of MWCNTs-COOH	Improving thermal, electrical, and mechanical properties of fluoroelastomer/amino functionalized multiwalled carbon nanotube composite	[223]
Jang et al.	MWCNT	3-Aminopropyltriethoxysilane	80°C	—	(i) The BET surface area 112.52 m^2 g-1 containing both micro- and meso-porous structure; (ii) Increased diameters as well as rougher, more corrugated surfaces; (iii) Interlayer spacing of the modified MWCNTs was estimated to approximately 14 nm	Removal of cesium from aqueous solution	[224]
Al-Shuja’a et al.	MWCNT	Thylene diamine (EDA) and O-phenylenediamine (OPDA)	90°C	—	(i) Formation of Poly (MWCNT/amide) with electrical conductivity in the range 4.5×10-6-5.3×10-6 S/cm	New strategy for chemically attachment of amide group on multiwalled carbon nanotube surfaces	[225]
Prabhavathi et al.	MWCNT	5,10,15,20-Mesotetra(4-aminophenyl) porphyrin	130°C	—	(i) MWCNT surface became bumpy after TAP functionalization; (ii) Electronic properties of MWCNTs were improved in the hybrid compared to raw MWCNTs	Synthesis, characterization, and photoluminescence properties of tetra(aminophenyl) porphyrin	[226]
Topcu et al.	CNT	Folic acid	0°C	—	(i) The diameter of the carbon nanotubes increased after grafting with folic acid molecules accompanied by the reducing aggregation of the carbon nanotubes	Potentiometric sensor	[227]
Zhou et al.	MWCNT	Polyethyleneimine (PEI)	80°C	—	(i) The PEI loading was dependent on both total functional group loading and the surface area of CNT; (ii) The maximum PEI loading could be obtained on CNT material with the highest total functional group loading (7.8 wt.%) and surface area (171.3 m^2/g)	Carbon dioxide capture	[228]