Intrinsic high refractive index polymers

As the ubiquity and complexity of optical devices grows, our technology becomes more dependent on specialized functional materials. One area of continued interest is in high refractive index polymers as lightweight, processable and inexpensive alternatives to silicon and glass. In addition to a high refractive index, optical applications require these polymers to be transparent and have a low optical dispersion. Both nanocomposite and intrinsic high refractive index polymers offer particular advantages and disadvantages. While nanocomposite high refractive index polymers have refractive indices above 1.80, the nanoparticle type, content and size can negatively affect storage stability and processability. Alternatively, intrinsic high refractive index polymers are prepared by introducing an atom or substituent with a high molar refraction into a polymer chain; the resultant polymers are easier to store, transport, tune and process. Polymers containing aromatic groups, halogens (except fluorine), phosphorus, silicon, fullerenes and organometallic moieties have all shown significant promise. Many factors can affect intrinsic high refractive index polymer performance including molecular packing, molar volume, chain flexibility and substituent content. This mini-review summarizes the principles behind and recent developments in intrinsic high refractive index polymers. © 2014 Society of Chemical Industry