ScienceNOW: In the world of nanotechnology, few things get as much billing as nanotubes. Experts say that these cylinders composed of one-molecule-thin sheets could someday be used in everything from superstrong jet engines to cancer cures. Now researchers think they've found a way to make large amounts of an elusive type of nanotube that could provide even more impressive applications.
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Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method
BNNTs if developed further would indeed be interesting but they would still have limits.
For example, any nanotube based body armour will also be very vulnernable and defeatable by high temperature incendiary weapons such as napalm, or high-powered rifles.
As for jet engines, some such engines have peak internal combustion temperatures in the 1,500 C range which is well above the 800 C temperature limits of BNNT.
However, BNNT could potentially (if mass-produced in scale) have profound uses in single stage to orbit space craft since such space craft will be much lighter when made largely of BNNT materials, a subject which I am deeply interested in but which is beyond the scope of subject and space limitations permitted in this blog.