Method for obtaining a material comprising a liquid crystal mix with a stabilized blue phase and optical article comprising this material

Patent metadata

Field	Value
Publication number	US-2018237694-A1
Application number	US-201615742150-A
Country	US
Kind code	A1
Filing date	Jul 6, 2016
Priority date	Jul 8, 2015
Publication date	Aug 23, 2018
Grant date	—

Abstract

Disclosed herein is a method for obtaining a material comprising mesogenic compounds forming a liquid crystal mix with a stabilized blue phase. The method includes the steps of a) inducing the liquid crystal mix, contained in a chemical composition, to form the blue phase, then b) illuminating the chemical composition with a light beam of visible wavelength in order to trigger the polymerization of monomers contained in the chemical composition, to obtain the material comprising the liquid crystal mix in the blue phase stabilized by the polymerized monomers. The chemical composition contains a mesogenic system and a chemical photo-initiator system adapted to trigger the polymerization of the monomers when illuminated by the light beam of visible wavelength, in which the mesogenic system includes the mesogenic compounds forming the liquid crystal mix, a chiral dopant adapted to induce the blue phase, and a monomer mix comprising the monomers adapted to polymerize.

First claim

1 . A method for obtaining a material comprising mesogenic compounds forming a liquid crystal mix with a stabilized blue phase, the method comprising:
a) inducing the liquid crystal mix, contained in a chemical composition, to form the blue phase; then b) illuminating the chemical composition with a light beam of visible wavelength in order to trigger the polymerization of monomers contained in the chemical composition, to obtain the material comprising the liquid crystal mix in the blue phase stabilized by the polymerized monomers, wherein: the chemical composition comprises a mesogenic system and a chemical photo-initiator system; the mesogenic system comprises
the mesogenic compounds forming the liquid crystal mix,
a chiral dopant adapted to induce the blue phase, and
a monomer mix comprising the monomers adapted to polymerize; and
the chemical photo-initiator system is adapted to trigger the polymerization of the monomers when illuminated by the light beam of visible wavelength.

2 . The method of claim 1 , further comprising selecting the mesogenic compounds so that a difference (Δn) between a second refractive index value (n 2 ) and a first refractive index value (n 1 ) is greater than or equal to 0.1,
wherein the material exhibits the first refractive index value (n 1 ) for an incident light beam when the liquid crystal mix is in the stabilized blue phase, and exhibits the second refractive index value (n 2 ) for the incident light beam when the mesogenic compounds of the liquid crystal mix align along a common direction (D) under the effect of an electromagnetic field.

3 . The method of claim 2 , wherein the selecting of the mesogenic compounds occur so that a difference between a minimum (n 2 min) of the second refractive index value (n 2 ) and the first refractive index value (n 1 ) is greater than or equal to 0.2, wherein the second refractive index value (n 2 ) of the material reaches the minimum (n 2 min) when the common direction (D) along which all the mesogenic compounds of the liquid crystal mix align under the effect of the electromagnetic field is parallel to the direction of the incident light beam.

4 . The method of claim 1 , wherein the chemical photo-initiator system contained in the material is colorless.

5 . The method of claim 4 , wherein the chemical photo-initiator system is colored when added to prepare the chemical composition, and photo-bleaches while illuminated with the light beam of visible wavelength to become colorless in the material.

6 . The method of claim 1 , wherein the mesogenic compounds contained in the mesogenic system are nematic liquid crystals selected from the group consisting of chemical formulas:

wherein:
R 1 to R 3 are each independently one of the following atoms or groups: H, F, CI, Br, I, CN, NO2, N-chlorosuccinimide, or an alkyl which is a straight chain or a branched chain, and which is unsubstituted, mono- or poly-substituted by F, CI, Br, I or CN;
X 1 to X 9 are each independently one of the following atoms or groups: H, F, CI, Br, I, CN, NO2, N-chlorosuccinimide or an alkyl which is straight chain or branched, and which is unsubstituted, mono- or poly-substituted by F, Cl, Br, I or CN; and
o, p, b and d are independent of each other and either 0 or 1.

7 . The method of claim 1 , wherein the monomer mix comprises:
low molecular weight reactive monomers of formula (III):

wherein
R 5 is one of the following: an H atom or an alkyl which is a straight or a branched chain, and
q is either 1, 2, or 3; and

high molecular weight reactive monomers, which optionally are mesogenic compounds, of formula (IV):

wherein r and s are each independently an integer from 1 to 12.

8 . The method of claim 1 , wherein the mesogenic system comprises:
from 2% to 70% of mesogenic compounds of formula (I):

from 2% to 70% of mesogenic compounds of formula (II):

from 0.5% to 35% of low molecular weight reactive monomers of formula (III):

and
from 0.5% to 35% of high molecular weight reactive monomers of formula (IV):

from 1% to 35% of chiral dopants,
wherein:
R 1 to R 3 are each independently one of the following atoms or groups: H, F, CI, Br, I, CN, NO2, N-chlorosuccinimide, or an alkyl which is a straight chain or a branched chain, and which is unsubstituted, mono- or poly-substituted by F, CI, Br, I or CN;
X 1 to X 9 are each independently one of the following atoms or groups: H, F, CI, Br, I, CN, NO2, N-chlorosuccinimide or an alkyl which is straight chain or branched, and which is unsubstituted, mono- or poly-substituted by F, CI, Br, I or CN;
o, p, b and d are independent of each other and either 0 or 1;
R 5 is one of the following: an H atom or an alkyl which is a straight or a branched chain;
q is either 1, 2, or 3; and
r and s are each independently an integer from 1 to 12.

9 . The method of claim 1 , wherein the chemical photo-initiator system is at least one selected from the group consisting of:
2,4-bis julolidenyl cyclopentanone with 2,2′,4-Tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-,4′,5′-diphenyl-1,1′-biimidazole and mercapto benzoxazole; rose Bengal dye and n-phenyl glycine; erythrosine B with triethanolamine initiator and N,N′-methylenebisacrylamide monomers; methylene blue and triethanolamine initiator; methylene blue and p-toluensulfonic acid; bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819); cyanine dye with 5,5′-Dichloro-11-diphenylamino-3,3′-diethyl-10,12-ethylenethiatricarbocyanine perchlorate (IR-140 initiator), with ethyl-di-methyl-amino-benzoate (electron donor) and tetrabromomethane; dibromofluorescein (xanthene dye) and N-phenylglycine; and 5,7-diiodo-3-butoxy-6-fluorone (H-Nu 470, C 17 H 14 I 2 O 3 ) with 2,4,5,7-Tetraiodo-3-hydroxy-6-fluorone (H-Nu 535, C 13 H 3 I 4 O 3 ) and 2,4,5,7-Tetraiodo-3-hydroxy-9-cyano-6-fluorone (H-Nu 635, C 14 H 2 I 4 NO 3 ,) with an amine and an iodonium salt co-initiator.

10 . The method of claim 1 , wherein the chiral dopant contained in the mesogenic system exhibits at least a cholesteric phase.

11 . The method of claim 1 , wherein the chiral dopant comprises at least one of the following compounds:
cholesterylnonanoate, R/S-811, R/S-1011, R/S-2011, R/S-3011, R/S-4011, R/S-5011, CB-15, ZLI-5011.

12 . An optical article of global variable refractive index, comprising the material obtained the method of claim 1 , sandwiched between at least two electrodes connected to a power source adapted to place the material in an electric field.

13 . The optical article of claim 12 , wherein the material is formed in a predetermined shape to manufacture the optical article.

14 . The optical article of claim 12 , wherein:
the material is formed

Assignees

• Essilor Int

Inventors

• Archambeau Samuel
• Cano Jean-Paul
• Guaza Sevastian

Classifications

• C09K19/588

  Heterocyclic compounds · CPC title

• G02F2001/13793

  Physics · mapped topic

• C09K2019/548

  stabilizing the alignment; Polymer stabilized alignment · CPC title

• G02F1/137

  characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering · CPC title

• G02F2203/06

  Polarisation independent · CPC title