  Various unique physical, chemical, mechanical and electronic properties of
carbon nanotube (CNT) make it very useful materials for diverse potential
application in many fields. Experimentally synthesized CNTs are generally found
in bundle geometry with a mixture of different chirality and present a unique
challenge to separate them. In this paper we have proposed the PAMAM dendrimer
to be an ideal candidate for this separation. To estimate efficiency of the
dendrimer in dispersion of CNTs from the bundle geometry, we have calculated
potential of mean forces (PMF). Our PMF study of two dendrimer wrapped CNTs
shows lesser binding affinity compared to the two bare CNTs. PMF study shows
that the binding affinity decreases for non-protonated dendrimer and for the
protonated case, the interaction is fully repulsive in nature. For both the
non-protonated as well as protonated cases, the PMF increases with increasing
dendrimer generations from 2 to 4 gradually compare to the bare PMF. We have
performed PMF calculations with (6,5) and (6,6) chirality to study the
chirality dependence of PMF. Calculated PMF for protonated dendrimer wrapped
chiral CNTs is more compared to the protonated dendrimer wrapped armchair CNTs
for all the generations studied. However, for non-protonated dendrimer wrapped
CNTs such chirality dependence is not very prominent. Our study suggests that
the dispersion efficiency of protonated dendrimer is more compared to the
non-protonated dendrimer and can be used as an effective dispersing agent in
dispersion of CNT from the bundle geometry.
