Method of preparing thin liquid crystal films

• US 5,368,770 A
• Filed: 06/01/1992
• Issued: 11/29/1994
• Est. Priority Date: 06/01/1992
• Status: Expired due to Term

• Current Assignee: Kent State University
• Original Assignee: Kent State University
• Inventors: Jakli, Antal, Saupe, Alfred
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US07/891,790
• Time in Patent Office: 911 Days
• Field of Search: 252/299.01, 252/299.5, 359/51, 359/52
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/542 Macromolecular compounds

Abstract

A liquid crystalline paste material is formed by polymerization of a solution containing a mesogenic solvent and monomeric material in bulk. The paste provides an improved method of preparing thin electrically addressable light modulating films by coating the paste onto a suitable substrate.

Claims

1. A method of producing a thin electrically addressable light modulating liquid crystalline film comprising the steps of:

a) preparing a solution comprising a polymerizable monomeric material in a mesogenic solvent having positive dielectric anisotropy;

b) polymerizing said solution in bulk until said monomeric material polymerizes and phase separates from the mesogenic solvent to form a spreadable liquid crystalline paste; and

thereafter,

c) coating said liquid crystal paste onto a substrate to form a thin electrically addressable film.

2. The method according to claim 1, wherein the polymerizing step is carried out when the mesogenic solvent is in the isotropic phase.

3. The method according to claim 1, wherein said monomeric material is added in an amount from about 0.5 to 5% by weight based on the weight of solvent and monomer.

4. The method according to claim 1, wherein the solution is photopolymerized.

5. The method according to claim 1, wherein the solution is thermally polymerized.

6. The method according to claim 1, which includes adding nematic liquid crystal as a component of the mesogenic solvent.

7. The method according to claim 6, further including adding a cholesteric liquid crystal material as a component of the mesogenic solvent.

8. A method of producing a thin electrically addressable light modulating liquid crystalline film comprising the steps of:

a) polymerizing a monomeric material to form a light transmissive polymer;

b) dissolving said light transmissive polymer in a mesogenic solvent having positive dielectric anisotropy;

c) cooling the solution in bulk until said polymer material phase separates from the mesogenic solvent to form a spreadable liquid crystalline paste; and

thereafter,

d) coating said liquid crystalline paste onto a substrate to form a thin electrically addressable film thereon.

9. The method according to claim 8, wherein said monomeric material is added in an amount from about 0.5 to 5% by weight based on the weight of the solvent and monomer.

10. The method according to claim 8, which includes adding nematic liquid crystal as a component of the mesogenic solvent.

11. The method according to claim 10, further including adding cholesteric liquid crystal material as a component of the mesogenic solvent.

12. A method of producing a thin electrically addressable light modulating liquid crystalline film comprising the steps of:

a) dissolving a monomeric material in a non-mesogenic solvent;

b) polymerizing said monomeric material;

c) adding a mesogenic solvent having positive dielectric anisotropy to the bulk solution of monomeric material and non-mesogenic solvent;

d) removing said non-mesogenic solvent until the polymerized monomeric material phase separates from said solution to form a spreadable liquid crystalline paste; and

thereafter,

e) coating said liquid crystalline paste onto a substrate to form a thin electrically addressable film thereon.

13. The method according to claim 12, wherein said monomeric material is added in an amount from about 0.5 to 5% by weight based on the weight of the solvent and monomer.

14. The method according to claim 12, which includes adding nematic liquid crystal material as a component of said mesogenic solvent.

15. The method according to claim 14, further including adding cholesteric liquid crystal material as a component of said mesogenic solvent.

16. An electrically addressable light modulating liquid crystalline paste formed by the process comprising the steps of:

a) preparing a solution comprising a polymerizable monomeric material in a mesogenic solvent having positive dielectric anisotropy;

b) polymerizing said solution in bulk until said monomeric material polymerizes and phase separates from the mesogenic solvent to form a spreadable liquid crystalline paste.

17. The liquid crystalline paste according to claim 16, wherein said polymerization is carried out when the mesogenic solvent is in the isotropic phase.

18. An electrically addressable light modulating liquid crystalline paste formed by the process comprising the steps of:

a) polymerizing a monomeric material to form a light transmissive polymer;

b) dissolving said light transmissive polymer in a mesogenic solvent having positive dielectric anisotropy;

c) cooling the solution in bulk until said polymer material phase separates from the mesogenic solvent to form a spreadable liquid crystalline paste.

19. An electrically addressable light modulating liquid crystalline paste formed by the process comprising the steps of:

a) dissolving a monomeric material in a non-mesogenic solvent;

b) polymerizing said monomeric material;

c) adding a mesogenic solvent having positive dielectric anisotropy to the bulk solution of monomeric material and non-mesogenic solvent;

d) removing said non-mesogenic solvent until the polymerized monomeric material phase separates from said solution to form a spreadable liquid crystalline paste.