화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.366, 2587-2594, 2001
Enhanced flexoelectric switching behaviour in the chiral nematic phase
In order to develop materials that exhibit enhanced flexoelectric switching in the chiral nematic phase we have identified mesogenic units that display inherently strong flexoelectric coupling capabilities. Here we examine the oxycyanobiphenyl (OCB) moiety: homologues from the nOCB series exhibit significant electro-optic switching effects when doped with a highly chiral additive. Here we have examined lower dielectric anisotropy materials, since they allow the flexoelectric response to be extended to high field amplitudes. We show that dielectric coupling strength can be low in symmetric bimesogenic molecules. The flexoelectric response of such a molecular structure is tested by doping a homologue from the series CBOnOCB with a chiral additive: very significantly we find that the optic axis is rotated through 2 phi = 45 degrees in < 50 mus on reversing the polarity of the field (amplitude E = +/-6 V mum(-1)). Subsequently we have synthesized room temperature chiral nematic materials that exhibit 2 phi greater than or equal to 90 degrees at E similar or equal to 10 V mum(-1).