Fabrication and Characterization of Polystyrene Colloidal Photonic Crystals on Soft Sodium Alginate Film

Three-dimensional (3D) colloidal photonic crystals (CCs) were fabricated on sodium alginate thin films through the vertical deposition self-assembly of monodisperse polystyrene (PS) microspheres. For the colloidal crystal fabrication, different sizes of microspheres (172 nm, 211 nm and 248 nm) were used to obtain colloidal crystals with different colours. The optical and structural properties of the colloidal crystals obtained on sodium alginate films were investigated and compared to the same colloidal crystals obtained on glass substrates. It was confirmed that the colloidal nanoparticles, self-assembled on sodium alginate, form a crystal structure that is similar to the one self-assembled on the glass substrate. The reflectance spectra of the colloidal photonic crystals showed different reflection peaks in the visible range for various particle sizes on both substrates with a slight shift (less than 5%) in the peaks for CCs on sodium alginate films.