Synthesis, Properties, and Photopolymerization of Liquid-Crystalline Oxetanes: Application in Transflective Liquid-Crystal Displays

• Published in: Advanced functional materials 2006-04, Vol.16 (6), p.791-798
• Main Authors: van der Zande, B. M. I., Roosendaal, S. J., Doornkamp, C., Steenbakkers, J., Lub, J.
• Format: Article
• Language: English
• Subjects: Heterocyclic compounds; Liquid crystals; Liquid-crystal displays; Photopolymerization
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200500359

Mixtures of liquid‐crystalline di‐oxetanes and mono‐oxetanes are made for the purpose of making birefringent films by photopolymerization. The composition of a di‐oxetane mixture that forms spin‐coated films of planarly aligned nematic monomers is reported. These films are photopolymerized in air. The molecular order of the monomers can be changed on the microscale to form thin films with alternating birefringent and isotropic parts by using a combination of photopolymerization and heating. The interface observed between the birefringent and isotropic 10 μm × 10 μm domains is very sharp and the films show hardly any surface corrugation. In addition, the polymerized films are thermally stable, making them very suitable for use as patterned thin‐film retarders in high‐performance transflective liquid‐crystal displays (LCDs) which satisfy customer demand for displays that are brighter and thinner and that deliver better optical performance than conventional LCDs with an external non‐patterned retarder. Thermally stable and non‐corrugated films with alternating birefringent and isotropic parts (see figure) are formed by changing the molecular order of a mixture of oxetane monomers on the microscale using a combination of heating and photopolymerization in air. The thermal stability of these films makes them candidates for use in high‐performance transflective liquid‐crystal displays.