Tailoring material composition for optimization of application-specific switchable holograms

• US 7,413,679 B1
• Filed: 12/29/2006
• Issued: 08/19/2008
• Est. Priority Date: 11/26/2002
• Status: Expired due to Fees

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Sutherland, Richard L., Pogue, Robert T., Shepherd, Christina K., Brandelik, Donna M., Natarajan, Lalgudl V.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US11/647,488
• Time in Patent Office: 599 Days
• Field of Search: 252/299.01, 252/299.5, 252/299.1, 428/1.1
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/54 Additives having no specific mesophase characterised by their chemical composition
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: C09K 2019/528 Surfactants
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition

Abstract

The process described herein offers the optimizing of performance parameters of holograms, such as reducing scattering effects in a polymer-dispersed liquid crystal optical element. In the process, an interfacial tension agent is added to a polymer-dispersed liquid crystal material. The polymer-dispersed liquid crystal material has a first material selected from the group consisting of a reactive ionic material, an aromatic material, a polypyrrole, and an acrylated or methacrylated acid of the type H₂CCH—(CO)O—R—(CO)OH, where R is a linear or branched alkyl chain. The polymer-dispersed liquid crystal material also has at least one type of liquid crystal material, a photoinitiator dye, and a co-initiator. The polymer-dispersed liquid crystal material is subjected to a polymerization. The interfacial tension agent reduces the size of liquid crystal droplets formed within the polymer-dispersed liquid crystal optical element during polymerization.

Claims

1. A polymer-dispersed liquid crystal element comprising:

an interfacial tension agent;

a polymer-dispersed liquid crystal material comprising;

a first monomer material selected from the group consisting of a reactive ionic material, an aromatic material, a polypyrrole, and an acrylated or methacrylated acid of the type H₂CCH—

(CO)O—

R—

(CO)OH, where R is a linear or branched alkyl chain;

at least one type of liquid crystal material;

a photoinitiator dye;

a co-initiator;

a co-monomer selected from the group consisting of fluorinated mono-acrylates and methacrylates; and

a cross-linking agent or a reactive diluent;

wherein the polymer-dispersed liquid crystal material is subjected to a polymerizing means.

2. The polymer-dispersed liquid crystal element according to claim 1, wherein the interfacial tension agent comprises a hydroxyl group.

3. The polymer-dispersed liquid crystal element according to claim 1, wherein the interfacial tension agent is of the type:

C_nH_(2n+1)COOH wherein n≦

18.

4. The polymer-dispersed liquid crystal element according to claim 1, wherein the interfacial tension agent is a long chain alkyl compound.

5. The polymer-dispersed liquid crystal element according to claim 1, wherein the reactive diluent is selected from the group consisting of decanoic acid and dodecanoic acid.

6. A process for reducing scattering effects in a polymer-dispersed liquid crystal optical element comprising:

adding an interfacial tension agent to a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising;

a first monomer material selected from the group consisting of a reactive ionic material, an aromatic material, a polypyrrole, and an acrylated or methacrylated acid of the type H₂CCH—

(CO)O—

R—

(CO)OH, where R is a linear or branched alkyl chain;

at least one type of liquid crystal material;

a photoinitiator dye;

a cross-linking agent; and

a co-initiator; and

subjecting the polymer-dispersed liquid crystal material to a polymerizing means, wherein the interfacial tension agent reduces the size of liquid crystal droplets formed within the polymer-dispersed liquid crystal optical element during polymerization of the polymer-dispersed liquid crystal material.

7. The process according to claim 6, wherein the interfacial tension agent comprises a hydroxyl group.

8. The process according to claim 6, wherein the interfacial tension agent is of the type:

C_nH_(2n+1)COOH wherein n≦

18.

9. The process according to claim 6, wherein the polymer-dispersed liquid crystal material further comprises a reactive diluent.

10. The process according to claim 6, further comprising the step of:

forming a polymer matrix upon polymerization of the polymer-dispersed liquid crystal material in an amount sufficient to increase the conductivity of the polymer matrix and cause a reduction in the switching voltage.

11. The process according to claim 6, wherein the first material is approximately 1.0 to 1.5 percent of the weight of the polymer-dispersed liquid crystal material.

12. The process according to claim 6, wherein the polymerizable means is selected from the group consisting of visible radiation, ultraviolet radiation, heat, electron beam and reactants.

13. The process according to claim 9, wherein the diluent comprises approximately 3 to 4 percent of the polymer-dispersed liquid crystal material.

14. The process according to claim 6, wherein the interfacial tension agent is a long chain alkyl compound.

15. The process according to claim 6, further comprising the step of adding a co-monomer.

16. The process according to claim 15, wherein the co-monomer is selected from the group consisting of fluorinated mono-acrylates and methacrylates.

17. The process according to claim 9, wherein the diluent is selected from the group consisting of decanoic acid and dodecanoic acid.

18. The process according to claim 9, further comprising the steps of:

exposing the polymer-dispersed liquid crystal material to white light for a predetermined amount of time; and

exposing the polymer-dispersed liquid crystal material to a heat cycle.

19. The process according to claim 18, wherein the heat cycle comprises the following temperatures in order:

approximately 25 degrees Celsius, approximately 75 degrees Celsius, and approximately 25 degrees Celsius.