| Summary: | 碩士 === 國立交通大學 === 材料科學與工程系所 === 96 === In order to improve the properties of H-bonded bent core mesogens,
there is two series for our research, one is mixtures of single hydrogen
bonded banana-shaped polymer doped with covalent bonded
banana-shaped liquid crystals；another is mixtures of single hydrogen
bonded banana-shaped compound doped with covalent bonded
banana-shaped polymer. The phases were demonstrated by polarized light
optical microscopy (POM), differential scanning calorimetry (DSC),
powder X-ray diffraction (XRD), and electro-optical properties based on
dielectric response as well as measurements of polarization reversal
current.
The temperature range of the B2 phase of mixtures was extended
from several degrees to about fifteen to thirty degrees due to the
contribution of covalent bonded LCs；for both series, as polymer is less
than 20 wt％, the spontaneous polarization (PS) shows up；moreover, the
spontaneous polarization (PS) of single H-bonded LCs was increased
from about 250 nC/cm2 to 500 nC/cm2 with the increasing of the
percentage of the covalent bonded mesogens linearly. The relationships
between Ps value and applied voltage were also studied. Saturated
applied voltage can be reduced by doping H-bonded mesogens in
covalent bonded LCs.
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