Structure transition of polymer-mediated colloidal crystals

1
Structure transition of polymer-mediated
colloidal crystals Chunrui Han et
al. Supervisor Luwei Zhou Department of Physics,
Fudan University, Shanghai 200433, China
The self-assembled colloidal crystals with
tunable structures are realized experimentally on
substrates with polymer brushes. Such
polymer-mediated colloidal crystals were found to
experience a series of in-layer structure
transitions including stable columnar,
polycrystalline, mixed square-hexagonal, square
(body-centered tetragonal), hexagonal structures
when the mass ratio of colloidal particles to
free polymers is adjusted from 0.125 to 10. Among
these structures, a large area interfacial square
structure which corresponds to the body-centered
tetragonal (BCT) structure in three dimensions is
first observed in the polymer-mediated colloidal
crystals.

• Conclusions
• By using free polymers and polymer brushes, we
  have experimentally demonstrated a method for
  fabricating a class of colloidal crystals with
  stable tunable crystalline structures
• 2. Such polymer-mediated colloidal crystals
  were found to experience a series of in-layer
  structure transitions including a stable square
  structure when we adjusted the mass ratio of
  colloidal particles to free polymers
• 3. We have proved that the square structure
  is BCT structure in 3-dimensions both in theory
  and experiment.

Reflectance spectrum of square and hexagon
structure
Band structure of BCT and FCC lattice