even orders-of-magnitude above other materials. As such, CNTs have been lauded
as some of the most perfect molecules that could exist.
CNTs come in a range of sizes and morphologies, each with its own specific
electronic, thermal, and mechanical properties; this, in itself, is a testament to the
collective value of these molecules in future applications. These allotropes range
from single-walled (SWNTs) to multi-walled CNTs (MWNTs), with a few special
subsets such as double-walled (DWNTs) and few-walled CNTs (FWNTs). Addingto
this complexity, each of these come in a range Ofhelicities (termed a CNT's
"chirality"), though this characteristic is typically only used when referring to
SWNTs; the chirality of a SWNT can determine metallic or semimetallic behavior,
and isolating each of these types of SWNTs is the subject of research focus to this
day [11].
Additionally, the idealized properties reported for CNTs generally assume a
perfect crystalline structure. Unfortunately, despite great efforts, highly-crystalline
CNTs are not experimentally viable in large quantities even by present day growth
procedures. Due to inherent difficulties in synthesis, even the CNTs generated by
today's highly-optimized methods are typically produced in a small yield of highly-
Crystalline CNTs or a large yield of highly-defective CNTs, with some processes
falling in the middle of those two extremes. Research still continues to perfect these
growth processes.
Given all of this, the CNTs produced in large quantities still have significant
utility. Despite their поп-perfect structure, they are typically much cheaper to