High-contrast thin-film polarizers by photo-crosslinking of smectic guest-host systems

\u3cp\u3eThe preparation of high-contrast thin-film polarizers by photo-crosslinking of smectic guest-hosts systems for use in liquid crystal displays (LCDs) is presented. Thin-film polarizers has the advantages of significant reduction in display and weight, and the positioning of the polarizers inside the cell eliminates all parallax-related issues and is beneficial to the robustness of the display. One possible approach to obtaining thin, coatable polarizers based on the use of lyotropic liquid-crystalline dyes that form a crystalline polarizer with sub-micrometer film thickness after coating and evaporation of the solvent. The low viscosity of the reactive liquid crystals facilitates easy alignment, while the in setu photopolymerization provides freedom in choosing the photopolymerization temperature and conditions enabling the selection of the optimum phase and molecular order. This thin-film technology could be an alternative to traditional sheet polarizers in LCD.\u3c/p\u3

Synthesis, properties, and photopolymerization of liquid-crystalline oxetanes:Application in transflective liquid-crystal displays

\u3cp\u3eMixtures 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.\u3c/p\u3

Preparation of monodisperse polymer particles and capsules by ink-jet printing

\u3cp\u3eMicron-sized particles with a narrow size distribution are prepared by ink-jet printing technology. Droplets of a polymer solution are printed with the nozzle submerged into an aqueous phase. The particles are formed upon removal of the solvent for the polymer. The particle size can be accurately predicted from the initial drop size and the polymer concentration. The method is also suitable for the preparation of monodisperse capsules with a well-defined core and shell using an additional non-solvent for the polymer. Hollow capsules are prepared by removal of the non-solvent from core of the capsules using freeze-drying. This leads to gas-filled capsules with a well-defined polymeric shell and a diameter in the range of 5 μm, which may be applied as an ultrasound contrast agent.\u3c/p\u3

Technologies towards patterned optical foils applied to transflective LCDs

\u3cp\u3eFor better front-of-screen performance for transflective LCDs, a technology with extra free optimization parameters for the optical stack is needed. Thin wet coatable retarders which enable adjustment of the optical activity on the (sub)pixel level have been developed. Isotropic domains have been created in nematic retardation films by thermal patterning or photopatterning. Employing such a patterned retarder in a transflective LCD leads to an LCD that is lighter and thinner with good reflectivity, high transmission, and low chromaticity at all gray levels and wide viewing angles. The patterned thin-film technology has been proven to be versatile and applicable in various LCD designs.\u3c/p\u3