Chiroptical filters from aqueous (hydroxypropyl) cellulose liquid crystals

✍ Scribed by Gérard Charlet; Derek Gray

• Book ID: 102734772
• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 627 KB
• Volume: 37
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1989.070370905

✦ Synopsis

An experimental procedure has been designed for the preparation of aqueous mesophases of (hydroxypropy1)cellulo.w (HPC) exhibiting a stable low turbidity. Sandwich chiroptical filters have been made from these right-handed cholesteric liquid crystals confined between two parallel glass plates. Their optical properties, studied with new circular polarizers prepared from oriented polyethylene films, depend on the mesophase thickness. Thin filters (liquid crystal thickness I 200 pm) reflect selectively up to 36% of normal incident light (i.e., 728 of the right-handed circularly polarized component) in a very narrow wavelength band (bandwidth I 10 nm). An increase of the reflected intensity is observed at higher sample thickness, although it is accompanied by an increasing loss of selectivity of the filter toward circularly polarized light. However, a range of thickness exists where both selectivity and reflectivity are close to their optimum values. The availability, low cost, and W resistance of (hydroxypropy1)cellulos.e make HPC-water liquid crystals attractive for optical applications.