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methacrylate) were synthesized by emulsion polymerization of the monomer in
the presence of a radical initiator or a cross-linking agent. CNT were found to
react mostly with radical-type oligomers. The modified tubes had an enhanced
adhesion to the polymer matrix, as could be observed by the improved mechani-
cal properties of the composite. A different approach to composite preparation
involves the attachment of atom transfer radical polymerization (ATRP) initiators
to the graphitic network. These initiators were found to be active in the polymer-
ization of various acrylate monomers. Recently prepared and characterized com-
posites of nanotubes with methyl methacrylate and tert-butyl acrylate. The former
composites were found to be insoluble in common solvents, while the latter were
soluble in a variety of organic media. The fabrication of nanotube polyaniline
composites via in situ chemical polymerization of aniline was studied by many
groups. Initially, a charge transfer interaction was suggested, whereas a covalent
attachment between the two components was described. The surface modifica-
tion of SWNT was reported recently via in situ Ziegler-Natta polymerization of
ethylene. The exact mechanism of nanotube-polymer interaction remains unclear,
althoughthe authors suggested that a possible cross-linking could take place be-
tween the two components. The development of an integrated nanotube-epoxy
polymer composite was reported by some authors. In the fabrication process, the
authors used functionalized tubes with amino groups at the ends. These moieties
could react easily with the epoxy groups and act as curing agents for the epoxy
matrix. The cross-linked structure was most likely formed through covalent bonds
between the tubes and the epoxy polymer. Multi-walled CNT were successfully
modified with polyacrylonitrile chains by applying electrochemical polymeriza-
tion of the monomer. The surface-functionalized tubes showed a good degree of
dispersion in DMF while further proofs of debundling were obtained by TEM
images [56].
1.1.6 CNT-COMPOSITES BASED ADSORBENTS
Potential practical applications of CNTs such as chemical sensors, field emis-
sion, electronic devices, high sensitivity nanobalance for nanoscopic particles,
nanotweezers, reinforcements in high performance composites, biomedical and
chemical investigations, anode for lithium ion batteries, super capacitors and hy-
drogen storage have been reported. Even though the challenges in fabrication
may prohibit realization of many of these practical device applications, the fact
that the properties of CNTs can be altered by suitable surface modifications can
be exploited for more imminent realization of practical devices. In this respect,
a combination of CNTs and other nanomaterials, such as nanocrystalline metal
oxide/CNTs, polymer/CNTs and metal filled CNTs may have unique properties
and research have therefore been focused on the processing of these CNT based
nano composites and their different applications [54, 57].
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