Liquid crystal composite and method of making

• US 5,745,198 A
• Filed: 06/27/1996
• Issued: 04/28/1998
• Est. Priority Date: 03/24/1994
• Status: Expired due to Term

• Current Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Original Assignee: Raychem Limited (TE Connectivity Limited)
• Inventors: Havens, John, Atkins, Harriette, Cheng, Jinlong, Gonzales, Anne, Di Zio, Kathleen, Reamey, Robert H.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/672,147
• Time in Patent Office: 670 Days
• Field of Search: 349/51, 349/52, 349/74, 349/98, 349/102, 349/86, 349/89, 349/90, 349/92, 349/93, 445/24, 445/25, 430/20, 428/1, 252/299.01, 252/299.1, 252/299.5, 264/4.1, 264/4.32, 264/4.33, 264/4.6
• US Class Current: 349/90
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal

Abstract

A method is disclosed for making a liquid crystal composite in which droplets of a liquid crystal material are dispersed in a polymer matrix. At least one further material separates the liquid crystal material from the polymer matrix. This construction permits the polymer matrix to be selected on the basis of its environmental properties and the further material to be selected on the basis of its orientational interactions with liquid crystal material. Light valves made from such a composite exhibit improved electro-optical properties.

Claims

1. A liquid crystal composite comprising plural volumes of liquid crystal material dispersed in a matrix material, wherein the liquid crystal material is at least partially separated from the matrix material by an interfacial material and an encapsulating material successively disposed around the liquid crystal material, wherein the interfacial material is selected from the group consisting of acrylates, methacrylates, epoxies, polyurethanes, polyureas, and siloxanes.

2. A liquid crystal composite comprising plural volumes of liquid crystal material dispersed in a matrix material, wherein the liquid crystal material is at least partially separated from the matrix material by an interfacial material and an encapsulating material successively disposed around the liquid crystal material, wherein the encapsulating material is selected from the group consisting of poly(vinyl alcohol), poly/vinyl pyrrolidone), poly(ethylene glycol), poly(acrylic acid) and its copolymers, poly(hydroxy acrylate), cellulose derivatives, epoxies, silicones, acrylates, polyesters, styrene-acrylic acid-acrylate terpolymers, and mixtures thereof.

3. A liquid crystal composite comprising plural volumes of liquid crystal material dispersed in a matrix material, wherein the liquid crystal material is at least partially separated from the matrix material by an interfacial material and an encapsulating material successively disposed around the liquid crystal material, wherein the matrix material is selected from the group consisting of polyurethanes, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene glycol), poly(acrylic acid) and its copolymers, poly(hydroxy acrylate), cellulose derivatives, epoxies, silicones, acrylates, polyesters, styrene-acrylic acid-acrylate terpolymers, and mixtures thereof.

4. A liquid crystal composite according to claim 3, wherein the interfacial material, encapsulating material, and matrix material are poly(2-ethylhexyl acrylate), poly(vinyl alcohol), and polyurethane, respectively.

5. A method of making a liquid crystal composite comprising plural volumes of liquid crystal material dispersed in a matrix material, wherein the liquid crystal material is at least partially separated from the matrix material by an interfacial material and an encapsulating material successively disposed around the liquid crystal material, comprising the steps of:

(a) forming capsules in which the liquid crystal material is successively surrounded by interfacial material and encapsulating material;

(b) dispersing the capsules in a medium in which the matrix material or a precursor thereof is present; and

(c) causing the matrix material or precursor thereof to set around the capsules, to form the liquid crystal composite.

6. A liquid crystal composite according to claim 5, wherein the liquid crystal material is a nematic liquid crystal material having positive dielectric anisotropy.

7. A liquid crystal composite according to claim 6, wherein the liquid crystal material contains a pleochroic dye.

8. A liquid crystal composite according to claim 5, wherein the interfacial material is selected from the group consisting of acrylates, methacrylates, epoxies, polyurethanes, polyureas, siloxanes, and mixtures thereof.

9. A liquid crystal composite according to claim 5, wherein the encapsulating material is selected from the group consisting of poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene glycol), poly(acrylic acid) and its copolymers, poly(hydroxy acrylate), cellulose derivatives, epoxies, silicones, acrylates, polyesters, styrene-acrylic acid-acrylate terpolymers, and mixtures thereof.

10. A liquid crystal composite according to claim 5, wherein the matrix material is selected from the group consisting of polyurethane, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene glycol), poly(acrylic acid) and its copolymers, poly(hydroxy acrylate), cellulose derivatives, epoxies, silicones, acrylates, polyesters, styrene-acrylic acid-acrylate terpolymers, and mixtures thereof.

11. A liquid crystal composite according to claim 5, wherein the interfacial material, encapsulating material, and matrix material are poly(2-ethylhexyl acrylate), poly(vinyl alcohol), and polyurethane, respectively.

12. A liquid crystal composite according to claim 5, wherein the encapsulating material is fixed in place by crosslinking or physical entanglement of molecular chains.