PDLC film or Polymer Dispersed Liquid Crystal film is a switchable privacy film consisting of micron-sized liquid crystal droplets, suspended and dispersed in an isotropic polymer matrix. With the right combinations of polymer and liquid crystal material, a PDLC smart film can be electrically charged and switched between a light scattering opaque state to a transparent, non-scattering state, also referred to as an “off” and “on” state, respectively. When a PDLC film is in its “off” state, it takes on a milky white appearance, obscuring vision. This is due to a mismatching of the film’s refractive index with the incoming light at the polymer-liquid crystal interface.
Upon the application of an electric field across the PDLC film, the molecules within the liquid crystal micro droplets align in a way that the higher relative permittivity of both the electric field and liquid crystal is parallel. As a result, the liquid crystal materials with positive dielectric anisotropy is parallel with their long-molecular axis, which are also aligned with the direction of the electric field.
In the “on” state of a PDLC smart film, the liquid crystal molecules’ ordinary refractive index becomes sufficiently close to that of the polymer matrix’s, so that incoming light no longer appears scattered. The film clears so that things on the other side of the glass become visible. Polymer dispersed liquid crystal films find great use in a wide variety of applications and devices, like switchable windows.
A crucial component of PDLC film is ITO or Indium Tin Oxide, which contains a mixture of tin and indium oxide, resulting in a semi-conductive substance with high electrical conductivity. Thin layers of this material are clear in the area of visible light, and their high electrical conductivity and transparency make them the best choice of material for manufacturing PDLC smart film products for various applications. Smart films eliminate the need for expensive window treatments and additional accessories like blinds and shades. They are excellent green building materials that can be used for electric curtains, switchable projection screens, glass display windows, glass enclosures, and even for decorative purposes.
About the Author:
Justin Zhang is a representative from SGV, the leading smart glass manufacturer and wholesaler of PDLC Films and smart glass material over a span of 10 years. The company has all necessary certifications from ISO, SGS, CE, ROHS, China 3C and many other international standards with 20 technical patents.
