Direct mapping of local director field of nematic liquid crystals at the nanoscale
Mesogenic compounds having a structure of Formula (I), (II) or (III): where A, B, X1, L, TG, m, and n are defined as in claim 1 . Compositions containing these compounds, articles made from these polymerized and prepolymerized compositions, and methods of estimating the elastic constants and anchoring constants of a liquid crystal materials and mapping topological defect structures in liquid crystals using these compounds.
1. A mesogenic compound having a structure of Formula (I):
wherein:
A is phenyl and B is pyridinyl or both A and B are pyridinyl;
wherein each L is positioned para to one another on each A or B ring and L is, independently at each occurrence, —CH(C═NOH)—, —C(O)N(R 1 )—, —OC(O)N(R 1 )—, or —N(R 1 )C(O)O—;
X 1 is NO 2 or CN;
Wherein R 1 is independently at each occurrence H or C 1-3 alkyl;
Each TG independently comprises an epoxy, glycidyl, acrylate, methacrylate, alkene, alkyne, or oxetane; m is independently 1, 2, or 3 at each occurrence; and
n is 1, 2, or 3.
2. The mesogenic compound of claim 1 , wherein:
A is phenyl and B is pyridinyl.
3. The mesogenic compound of claim 1 , wherein A is pyridinyl and the relative positions of X 1 with respect to ring A are:
4. The mesogenic compound of claim 1 , wherein n is 1 and X 1 is NO 2 .
5. The mesogenic compound of claim 1 , wherein TG independently comprises an epoxy, alkene, or glycidyl.
6. The mesogenic compound of claim 1 , wherein TG is the same epoxy or glycidyl in both occurrences.
7. The mesogenic compound of claim 1 , wherein m is 1 or 2 and the same at each occurrence.
8. The mesogenic compound of claim 1 , wherein m is 1.
9. The mesogenic compound of claim 1 , wherein A and B are pyridinyl.
10. A composition comprising the mesogenic compound of claim 1 and a crosslinking agent or at least one nanodimensioned dopant, or both a crosslinking agent and at least one nanodimensioned dopant.
11. An article comprising the composition of claim 10 superposed on a nano and micro-dimensionally patterned substrate.
12. A liquid crystal composition or polymer precursor comprising a crosslinkable mesogenic compound of claim 1 , wherein the liquid crystal composition or polymer precursor:
(a) is crosslinked with at least one crosslinking agent; or
(b) further comprises a nanodimensioned dopant; or
(c) is a nematic liquid crystal; or
(d) is a combination of two or more of (a), (b), and (c).
13. An optical film, coating, or encapsulant comprising a liquid crystal composition or polymer precursor of claim 12 that exhibits high positive birefringence.
14. An optical waveguide comprising a liquid crystal composition or polymer precursor of claim 12 .
15. An actuator, sensor, artificial muscle, mechanically or thermally tunable laser device, a mechanically or thermally tunable temperature sensor, an optical polarizer, cosmetic pigment, photovoltaic substrate, or fuel cell membrane comprising a polymer precursor comprising a crosslinkable mesogenic compound of claim 1 and an optional chiral dopant.
16. A method of estimating the elastic constant of a liquid crystal material comprising: incorporating a mesogenic compound of claim 1 into a matrix of polymerized liquid crystal material and imaging the matrix using scanning electron microscopy.
17. A method of mapping defect structures in liquid crystals comprising: incorporating a mesogenic compound of claim I into a polymerized matrix of the liquid crystal, the method further comprising imaging the defect structures or orientation/alignment of the liquid crystals or LC molecules through the defect fractures of the polymerized liquid crystal matrix using scanning electron microscopy.
18. A mesogenic compound having a structure of Formula (I):
wherein:
A and B are pyridinyl;
wherein each L is positioned para to one another on each A or B ring and L is, independently at each occurrence, —CH(C═NOH)—, —C(O)N(R 1 ), —OC(O)N(R 1 )—, or —N(R 1 )C(O)O—;
X 1 is CN;
wherein R 1 is independently at each occurrence H or C 1-3 alkyl;
Each TG independently comprises an epoxy, glycidyl, acrylate, methacrylate, alkene, alkyne, or oxetane;
m is independently 1, 2, or 3 at each occurrence; and
n is 1, 2, or 3.