Liquid crystal compositions, mixtures, elements, and dimmable devices
Described herein are liquid crystal compositions that can allow for the adjustment of their refractive indices by the application of an electric field. Also described herein are liquid crystal mixtures containing these compositions. In addition, selectively dimmable reverse-mode polymer dispersed liquid crystal (PDLC) elements and devices using these compositions are also described, which are transparent when no or low voltage is applied and opaque when a voltage or high voltage is applied.
1. A liquid crystal composition comprising a first compound, wherein the first compound comprises:
or a combination thereof.
2. The liquid crystal composition of claim 1 , further comprising a second compound of Formula II:
wherein X 1 is substituted phenyl, substituted cyclohexane, substituted biphenyl, or substituted cyclohexyl-benzene; and
Y 1 is C 1-6 alkyl, C 1-6 alkyloxy, —CN, —NCS, F, Cl, OH, NO 2 , —NR a R b , —NHCOR a , —NHSO 2 R a , —OCOR a , or —SO 2 R a ; —C(O)R a , —C(O)OR a , —C(O)NHR a , or —C(O)NR a R b .
3. The liquid crystal composition of claim 2 ,
wherein the second compound is:
or a combination thereof.
4. A liquid crystal element comprising:
a transparency changing layer; and
at least two alignment layers each bounding to one side of the transparency changing layer; wherein the transparency changing layer comprises a first liquid crystal compound comprising:
or a combination thereof.
5. The liquid crystal element of claim 4 , wherein the transparency changing layer comprises a second liquid crystal compound, wherein the second liquid crystal compound is:
or a combination thereof.
6. The liquid crystal element of claim 5 , wherein the second liquid crystal compound is 6CHBT, and the second liquid crystal compound is present in an amount of about 0 wt % to about 25 wt %, and the liquid crystal element further comprises 5CB in an amount of about 35 wt % to about 70 wt %, 7CB in an amount of about 13 wt % to about 31 wt %, 8OCB in an amount of about 0 wt % to about 20 wt %, 5CCB in an amount of about 0 wt % to about 16 wt %; and 5CT in an amount of about 5.5 wt % to about 10.5 wt %, provided that the total weight percentage of the liquid crystal compounds in the liquid crystal element including the liquid crystal composition is 100 wt %.
7. A selectively dimmable device comprising:
a liquid crystal element of claim 4 ;
at least two conductive substrates; and
a voltage source;
wherein the first and second conductive substrates define a gap between them;
wherein the liquid crystal element disposed between the first and second conductive substrates within the gap;
wherein the substrates and the element are in electrical communication with the voltage source such that when a voltage is applied from the voltage source, an electric field is generated across the liquid crystal element.
8. The device of claim 7 , wherein the device has a haze of about 40% to about 50% when a voltage of 20 volts or above is applied across the device and wherein the device has a haze of about 5% or less when no voltage, or when a voltage of 10 volts or less, is applied.
9. The device of claim 7 , wherein the substrates are flexible so that the device forms a flexible sheet.