  Synthetic opals, based on self-assembly of polymeric nanoparticles generally
produces fainted/pale structural colors due to too many lattice flaws in the
structures. Here we produces carbon nanotubes (CNTs) incorporated high quality
3D photonic opals (PC-CNT) by evaporative self-assembly. Although the CNTs make
up only 0.01% of the fabricated photonic opal, their controlled incorporation
has dramatic effect to change the color of the photonic crystals from milky
white to intense red. Microscopic study suggest that CNT incorporation did not
affect the lattice ordering of the photonic crystals. The tunability of
structural colors, as a function of incident angle, were tested and varied
against Bragg-Snell law. Furthermore, we tested mechanochromic sensing of the
photonic opals, demonstrating their potential as visual indicators. This
tunable PC-CNT brings many possibilities including strain sensing or structural
health care monitoring, as well as being of fundamental interest.
