  We present a simple one-pot co-assembly method for the synthesis of
hierarchically structured pigment particles consisting of silica inverse-opal
bricks that are doped with plasmonic absorbers. We study the interplay between
the plasmonic and photonic resonances and their effect on the visual appearance
of macroscopic collections of photonic bricks that are distributed in
randomized orientations. Manipulating the pore geometry tunes the wavelength-
and angle-dependence of the scattering profile, which can be engineered to
produce angle-dependent Bragg resonances that can either enhance or contrast
with the color produced by the plasmonic absorber. By controlling the overall
dimensions of the photonic bricks and their aspect ratios, their preferential
alignment can either be encouraged or suppressed. This causes the Bragg
resonance to appear either as uniform color travel in the former case or as
sparse iridescent sparkle in the later case. By manipulating the surface
chemistry of these photonic bricks, which introduces a fourth length-scale of
independent tuning into our design, we can further engineer interactions
between liquids and the pores. This allows the structural color to be
maintained in oil-based formulations, and enables the creation of dynamic
liquid-responsive images from the pigment.
