Liquid crystal film, method for preparing the film, temperature-responsive device comprising the film, and circular polarizer made therefrom

A method for preparing a liquid crystal film, wherein the method includes the following steps:

• providing a composition reaction system containing a polymerizable composition, wherein the composition comprises a photoinitiator, a cholesteric LC material, and a chiral material capable of hydrogen-bond-assisted self-assembly (HBASA);
• and
• applying a UV irradiation to the polymerizable composition such that a polymerization reaction of the monomer occurs in the composition reaction system;
• wherein the cholesteric LC material is a composition comprising:
• a polymerizable chiral LC monomer of 5-20 weight parts,
• a small molecular nematic LC of 65-90 weight parts, and
• a chiral additive of 5-15 weight parts;
• the amount of the photoinitiator is 0.5-5 weight parts;
• and
• the ratio by mass of the cholesteric LC material to the HBASA chiral material is in the range of (4-20):
• 1.

A temperature-responsive device, wherein the device comprises a liquid crystal film, wherein the liquid crystal film comprises a composite material formed upon UV irradiation of a polymerizable composition comprising a photoinitiator, a cholesteric LC material, and a chiral material capable of hydrogen-bond-assisted self-assembly (HBASA),

• wherein the liquid crystal film can exhibit a property of broad-band reflection at a temperature equal to or higher than the H-bond breaking temperature of the HBASA chiral material;
• wherein the cholesteric LC material is a composition comprising:
• a polymerizable chiral LC monomer of 5-20 weight parts,
• a small molecular nematic LC of 65-90 weight parts, and
• a chiral additive of 5-15 weight parts;
• the amount of the photoinitiator is 0.5-5 weight parts;
• and
• the ratio by mass of the cholesteric LC material to the HBASA chiral material is in the range of (4-20):
• 1.

A circular polarizer, wherein the circular polarizer is prepared from a liquid crystal film, wherein the liquid crystal film comprises a composite material formed upon UV irradiation of a polymerizable composition comprising a photoinitiator, a cholesteric LC material, and a chiral material capable of hydrogen-bond-assisted self-assembly (HBASA),

• wherein the liquid crystal film can exhibit a property of broad-band reflection at a temperature lower than the H-bond breaking temperature of the HBASA chiral material;
• wherein the cholesteric LC material is a composition comprising:
• a polymerizable chiral LC monomer of 5-20 weight parts,
• a small molecular nematic LC of 65-90 weight parts, and
• a chiral additive of 5-15 weight parts;
• the amount of the photoinitiator is 0.5-5 weight parts;
• and
• the ratio by mass of the cholesteric LC material to the HBASA chiral material is in the range of (4-20):
• 1.

A composite material useful for a liquid crystal film, wherein the composite material comprises a chiral material capable of hydrogen-bond-assisted self-assembly (HBASA) and a polymer network of a cholesteric LC material, and the HBASA chiral material is dispersed in and restrained by the polymer network;

• wherein the cholesteric LC material is a composition comprising:
• a polymerizable chiral LC monomer of 5-20 weight parts,
• a small molecular nematic LC of 65-90 weight parts, and
• a chiral additive of 5-15 weight parts;
• the amount of the photoinitiator is 0.5-5 weight parts;
• and
• the ratio by mass of the cholesteric LC material to the HBASA chiral material is in the range of (4-20):
• 1.