%0 Journal Article
%T Optical Properties of the Self-Assembling Polymeric Colloidal Systems
%A Alexandra Mocanu
%A Edina Rusen
%A Aurel Diacon
%J International Journal of Polymer Science
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/238567
%X In the last decade, optical materials have gained much interest due to the high number of possible applications involving path or intensity control and filtering of light. The continuous emerging technology in the field of electrooptical devices or medical applications allowed the development of new innovative cost effective processes to obtain optical materials suited for future applications such as hybrid/polymeric solar cells, lasers, polymeric optical fibers, and chemo- and biosensing devices. Considering the above, the aim of this review is to present recent studies in the field of photonic crystals involving the use of polymeric materials. 1. Photonic Crystals Nanomaterials with well-defined 3D repetitive arrays have found application in photonic devices, sensors, selective membranes, and even microchips. Compared to a classic crystalline array, colloidal spherical particles replace the molecules, atoms, or ions in hexagonal close packed (HCP) structure or cubic close packed (CCP) structures [1¨C3] (Figure 1). Figure 1: Three-dimensional arrays: (a) HCP, (b) CCP [ 3]. Colloidal particles are able, through self-assembly processes, to be arranged into 3D structures leading to colloidal crystals. The resulting materials revealed interesting properties, presenting similar optical characteristics with synthetic opal and photonic crystals (Figure 2). One of the most facile routes for obtaining photonic crystals is based on the employment of polymer colloids with self-assembling properties [3¨C5]. Figure 2: (a) Synthetic opal; (b) structure of a photonic crystal [ 4]. A photonic crystal is a periodic nanostructured material that influences the propagation of electromagnetic waves in a similar manner as a semiconductor does for electrons [3]. Although photonic crystals have been studied since 1887, with one of the pioneers being Rayleigh [6], the term has been introduced only in 1987, after the papers of two physicist working independently Yablonovitch and John [7, 8]. In order to understand the behavior of photons inside a photonic crystal it is possible to compare it with the motion of electrons and vacancies in a semiconductor material as mentioned above. A proper example of photonic crystals occurring in nature is opals, which contain a natural periodic microstructure of silica microspheres of 15¨C900£¿nm, responsible for their iridescent color [9]. This structure allows the propagation of the photons through the crystal, while the interaction between the silica spheres and light makes possible the formation of allowed and forbidden energy bands, also
%U http://www.hindawi.com/journals/ijps/2013/238567/