Evaluation of 4-alkoxy-40-nitrobiphenyl liquid crystals for use in next generation scattering LCDs

TY - JOUR

T1 - Evaluation of 4-alkoxy-40-nitrobiphenyl liquid crystals for use in next generation scattering LCDs

AU - Mandle, Richard

AU - Cowling, Stephen James

AU - Goodby, John William

N1 - © The Royal Society of Chemistry 2017

PY - 2017/8/18

Y1 - 2017/8/18

N2 - We have prepared nine members of the 4-alkoxy-40-nitrobiphenyl family of liquid crystals and evaluatedtheir thermal behaviour by a combination of polarised optical microscopy, differential scanningcalorimetry and small angle X-ray scattering, as well as in single pixel scattering devices for use inbacklight free liquid crystal displays (LCDs). Whereas homologues with shorter terminal aliphatic chainsare nematogenic, those with longer aliphatic chain lengths exhibit an additional smectic A phase,identified as the subtype SmAD by SAXS with all materials having a D/L ratio (smectic layer spacingdivided by molecular length) of 1.4. When doped with 0.1 wt% hexadecyltrimethylammonium perchloratewe observed that the SmAD phase of compound 9 could be switched with a relatively low voltage (58VRMS, roughly half that required for the analogous nitrile). This apparent reduction in threshold voltage,which occurs as a consequence of switching from a nitrile- to a nitro- group, provides a new impetus tostudy alternative polar terminal groups when designing host materials for smectic A scattering devices.

AB - We have prepared nine members of the 4-alkoxy-40-nitrobiphenyl family of liquid crystals and evaluatedtheir thermal behaviour by a combination of polarised optical microscopy, differential scanningcalorimetry and small angle X-ray scattering, as well as in single pixel scattering devices for use inbacklight free liquid crystal displays (LCDs). Whereas homologues with shorter terminal aliphatic chainsare nematogenic, those with longer aliphatic chain lengths exhibit an additional smectic A phase,identified as the subtype SmAD by SAXS with all materials having a D/L ratio (smectic layer spacingdivided by molecular length) of 1.4. When doped with 0.1 wt% hexadecyltrimethylammonium perchloratewe observed that the SmAD phase of compound 9 could be switched with a relatively low voltage (58VRMS, roughly half that required for the analogous nitrile). This apparent reduction in threshold voltage,which occurs as a consequence of switching from a nitrile- to a nitro- group, provides a new impetus tostudy alternative polar terminal groups when designing host materials for smectic A scattering devices.

U2 - 10.1039/c7ra06886g

DO - 10.1039/c7ra06886g

M3 - Article

SN - 2046-2069

JO - RSC Advances

JF - RSC Advances

IS - 64

ER -