Surface modified latex particles: Synthesis and self-assembling into photonic crystals

The capability of monodisperse carboxylated particles of poly(methyl methacrylate) and of styrene copolymers with glycidyl methacrylate or with methacrylic acid for self-assembling into thin films exhibiting properties of photonic crystals was studied in relation to their polymer nature, carboxyl group distribution, and to the compositions of the dispersion medium. These particles were capable of self-assembling from their dispersions and forming close-packed three-dimensional ordered arrays on glass slides. The poly(styrene-co-methacrylic acid) particles revealed to be the best choice as the building blocks for photonic crystals formation. To ensure the appropriate surface structure of the particles and narrow particle size distribution in the submicron range the effects of reaction mixture pH, chain-transfer agents, and initiator concentration were investigated subsequently. The Bragg reflection spectra from the (1 1 1) planes of their ordered structures showed a predominant high-reflectance peak corresponding to photonic band gap caused by 3D periodicity of refractive index. The experimental spectra obtained for polarized light at different angles of incidence were well simulated in the theoretical calculations.