Nucleation carbon nanotubes

Park KJ, Jung D (2007) Enhancement of nucleate boiling heat transfer using carbon nanotubes. International Journal of Heat and Mass Transfer 50 4499 1502. 

Ni(CO)4 is the sole binary carbonyl complex of the elements of group 10 that is stable (Table 8.1). However, very few studies in which Ni(CO)4 is used in the preparation of catalysts have been reported [43]. This is probably due to the difficulty of manipulation of Ni(CO)4 and its very high toxicity. However, surface Ni(CO)4 species have been identified after the interaction of CO with highly dispersed supported nickel catalysts prepared by other routes [44]. Recent interest in the use of Ni(CO)4 has focused on the controlled production of nickel nanoparticles for specific purposes, such as in automotive converters [45]. The use of nickel tetracarbonyl as an agent for the nucleation process in the growth of single-wall carbon nanotubes has also been reported [46]. 

The incorporation of carbon nanotubes (CNT)s into polymer matrices has resulted in composites that exhibit increased thermal stability, modulus, strength, electrical and optical properties (33-35). Several investigations have concluded that carbon nanotubes can also act as a nucleating agents for polymer crystallization (36,37). 

K. Ryan, M. Cadek, V. Nicolosi, S. Walker, M. Ruether, A. Fonseca, J. Nagy, W. Blau, and J. Coleman, Multiwalled carbon nanotube nucleated crystallization and reinforcement in poly (vinyl alcohol) composites, Synth. Met., 156(2-4) 332-335, February 2006. 

The methods of preparation discussed above do not involve any template and the nanoparticles of the oxide or the trisulfide act as nucleation centers for tube growth. Recently, CNTs have been used as templates to grow MoS2, WS2 and NbS2 coated carbon nanotubes, some of which contain 1-2 layers of the chalcogenide at the exterior. " The CNTs were coated with the metal oxide or its precursor and treated in a H2S/H2/N2 atmosphere at elevated temperatures to convert the oxide to the sulfide However, the CNT core was not removed in the nanostructures (Fig. IS). 

Note that PVA is not the only polymer whose ciystallinity can be enhanced by nanotubes. Other studies (24-28) have indeed shown that carbon nanotubes can act as nucleating sites for several other polymers. It is also important to note that most studies were focused on composites with a low fraction of carbon nanotubes. When the nanotube content increases in the composite, the control... 

V.L. Kuznetsov, A.N. Usoltseva, A.L. Chuvilin, E.D. Obraztsova, J.M. Bonard, Ther modynamic Analysis of Nucleation of Carbon Deposits on Metal Particles and its Implication for the Growth of Single Wall carbon Nanotubes, Phys. Rev. B 64 (23) (2001) 5401 5408. 

B.R Grady, F. Pompeo, R.L. Sbambaugh, and D.E. Resasco, Nucleation of polypropylene crystallization by single-walled carbon nanotubes, J. Phys. Chem. B, 106, 5852-5858 (2002). 

---