Well, polymers and reinforcement fiber technology are continuing to
improve. You can even buy carbon-fiber reinforced polymers these days,
with superduper tensile strength. But I would imagine that kevlar,
spectra, vectran would have enough strength to do the job for a small
personal transportation vehicle. They would be able to handle the high
pressures.

To ease the load requirements, the rotor could be 4-vaned. Each pair
of opposing vanes could have a commonly inflated structure -- that way
if a single vane suffered a rupture, then it and its opposing partner
could be deflated/depressurized, while the remaining pair of rotor
vanes would take the load while you landed. Or why not even a 6-way
rotor?

Someone who responded to my posting suggested weighting the rotor tips
for flywheel effect. The centrifugal force from the weighted tips
would help to keep the rotors rigid and reduce the possibility of
buckling. Flywheel energy could also help in the event of an unpowered
landing due to engine failure.