Lowering of Electrostatic Actuator Driving Voltage and Increasing Generated Force Using Spontaneous Polarization of Ferroelectric Nematic Liquid Crystals (Adv. Phys. Res. 1/2022)

The Emergence of a Polar Nematic Phase: A Chemist's Insight into the Ferroelectric Nematic Phase

“…Materials Based on DIO DIO, as was mentioned earlier, is one of the archetypal materials which exhibits the ferroelectric nematic phase. DIO has a structure characterised by a dioxane ring at one terminus and a fluorinated biphenyl at the other joined by an ester linking group which gives the molecule a large longitudinal dipole, calculated to be 9.4 D, [7,48] and as was described previously this appears to be required for the N F phase to form. The calculation of the molecular dipole in these types of compounds have been widely undertaken using density functional theory, however, in order to account for the different basis sets used, the calculation method for each dipole has been reported in the footnotes of the tables.…”

“…Compound 17 had 2 fluorines meta to the terminal butoxy chain whereas compound 18 had no fluorination at those positions, both compounds, however, did not exhibit the N F phase. Nishimura et al [48] also reported compound 19 with the dioxane ring replaced by a cyclohexane moiety and a pentyl terminal chain. Li et al [18] reported compound 20 which had a similar molecular design to compound 18 but with a methoxy terminal chain.…”

“…Most of the convenient or simple modifications that can be made to these structures destabilise the N F phase. Also included in Table 4, are compounds 17 and 18 reported by Nishimura et al [48] who replaced the dioxane ring with a butoxy terminal chain and a dimethylamino group, respectively. Compound 17 had 2 fluorines meta to the terminal butoxy chain whereas compound 18 had no fluorination at those positions, both compounds, however, did not exhibit the N F phase.…”

“…The previous examples related to DIO have all had three aromatic rings incorporated into the molecular backbone, in Table 6 materials with only two aromatic rings are shown. [18,48] None of these compounds exhibit the N F phase, regardless of the composition of the substituents on the aromatic rings. Clearly removing one aromatic ring reduces the shape anisotropy of these materials compared to the compounds with three rings, as well as reducing the intermolecular interactions between the mesogenic units, and hence the liquid crystalline phase behaviour is suppressed.…”

High-κ elastomer with dispersed ferroelectric nematic liquid crystal microdroplets

“…28,29 Additionally, their low-voltage driving electric field response is attractive for flexible electronics applications. 30,31 The extension of the N F phase to 'ferroelectric' polymers shows great promise. 32,33 The intriguing combination of a giant dielectric constant, high polarization density, and fluidity positions N F LC as a desirable candidate for use as a liquid ferroelectric filler in high-k and stretchable composite materials.…”