Phase separated composite organic film and methods for the manufacture thereof

• US 5,949,508 A
• Filed: 12/10/1997
• Issued: 09/07/1999
• Est. Priority Date: 12/10/1997
• Status: Expired due to Fees

• Current Assignee: Kent State University
• Original Assignee: Kent State University
• Inventors: Vorfloussev, Valeri, Kumar, Satyendra
• Primary Examiner(s): Dudek, James A.
• Application Number:
  US08/988,146
• Time in Patent Office: 636 Days
• Field of Search: 349/86, 349/88, 349/122, 349/184
• US Class Current: 349/122
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/141 using ferroelectric liquid crystals

Abstract

A light modulating cell comprises a pair of substrates, alignment layers disposed on at least one of the substrates and a solution of polymerizable prepolymer and low molecular weight organic material disposed between the pair of substrates. The solution is phase separated and forms a layer of polymeric material and a layer of organic material between the two substrates. An external force may then be applied across the substrates to alter the optical appearance of the layer of organic material from one state to another. A photo-sensitive layer may also be provided in the cell.

Claims

1. A light modulating cell, comprising:

a pair of opposed substrates;

an alignment layer disposed on at least one of said opposed substrates facing the other of said opposed substrates; and

a composite material phase separated into a layer of polymeric material primarily disposed adjacent the other of said opposed substrates, and a layer of low molecular weight (LMW) organic material primarily disposed adjacent to one of said substrates with said alignment layer.

2. The light modulating cell according to claim 1, further comprising:

an electrode layer disposed on each said substrate facing both said layers; and

an electrical power source connected to said electrode layers for applying an electric field to alter the optical appearance of the cell.

3. The light modulating cell according to claim 1, further comprising:

a polarizer disposed on each of said substrates.

4. The light modulating cell according to claim 1, wherein said composite material is formed into said layers in substantially planar form by phase separation from a solution of prepolymer and LMW organic material which has anywhere between about 10% to about 90% prepolymer of the total weight of said solution.

5. The light modulating cell according to claim 4, wherein said layer of LMW organic material contains substantially uniformly sized ridges of polymer material integral with said layer of polymeric material and the other of said substrates.

6. The light modulating cell according to claim 4, wherein said layer of LMW organic material is a layer of ferroelectric liquid crystal.

7. The light modulating cell according to claim 6, wherein said layer of ferroelectric liquid crystal adheres to said alignment layer when said solution is phase separated.

8. The light modulating cell according to claim 1, wherein said layer of LMW organic material is selected from the group consisting of ferroelectric liquid crystal, nematic liquid crystal, cholesteric liquid crystal, anti-ferroelectric liquid crystal, and polymerizable monomers.

9. The light modulating cell according to claim 1, wherein said layer of polymeric material includes additives.

10. The light modulating cell according to claim 1, wherein said layer of polymeric material includes multi-functional groups attached to the polymer.

11. The light modulating cell according to claim 1, further comprising

a reflective element on one of said substrates on a side opposite said cell gap;

and

a polarizer on the other of said substrates on a side opposite said cell gap.

12. The light modulating cell according to claim 11, further comprising:

a polarizer disposed between said reflective element and said one substrate.

13. The light modulating cell according to claim 1, further comprising:

an alignment layer disposed on said substrate adjacent to said layer of polymeric material.

14. The light modulating cell according to claim 1, further comprising:

a photo-sensitive layer disposed between said alignment layer and said substrate.

15. A method for fabricating a phase separated composite organic film, comprising the steps of:

preparing a solution of prepolymer and low molecular weight (LMW) organic material;

providing a pair of substrates with a cell gap therebetween;

permanently disposing said solution into said cell gap; and

inducing phase separation of said solution to form at least one layer of polymeric material primarily disposed adjacent to one of said pair of substrates and a layer of LMW organic material primarily disposed adjacent the other of said pair of substrates.

16. The method according to claim 15, further comprising the step of:

providing an alignment layer on one of said substrates facing the other of said substrates adjacent said layer of LMW organic material.

17. The method according to claim 16, further comprising the step of:

providing an alignment layer on the other of said substrates adjacent said layer of polymeric material.

18. The method according to claim 16, wherein said step of inducing phase separation comprises the step of:

exposing said substrate without said alignment layer to ultraviolet light which polymerizes said polymeric material adjacent at least said substrate opposite said substrate with said alignment layer.

19. The method according to claim 18, further comprising the steps of:

providing said solution with between about 10% to about 90% prepolymer of the total weight of said solution; and

providing ferroelectric liquid crystal for said LMW organic material.

20. The method according to claim 19, further comprising the steps of:

providing a polarizer on both said substrates opposite said cell gap;

providing an electrode on each said substrate opposite said polarizers; and

connecting a power source to said electrodes for the purpose of driving said ferroelectric liquid crystal from one optical state to another.

21. The method according to claim 19, further comprising the steps of:

providing a reflective element on one of said substrates opposite said cell gap;

providing electrodes on each said substrate adjacent said cell gap; and

connecting a power source to said electrodes for the purpose of driving said ferroelectric liquid crystal from one optical state to another.

22. The method according to claim 21, further comprising the step of:

providing a polarizer between said reflective element and said one substrate.

23. The method according to claim 15, wherein said step of inducing phase separation is selected from the group of steps consisting of polymerization inducement, thermal inducement, and solvent inducement.

24. A light modulating cell, comprising:

a pair of opposed substrates; and

a composite material having prepolymer and low molecular weight (LMW) organic material, wherein said composite material is phase separated to form;

a layer of polymeric material primarily adjacent one of said substrates; and

a layer of LMW organic material primarily adjacent the other of said substrates.

25. The light modulating cell according to claim 24, further comprising:

an electrode layer disposed on each said substrate facing both said layers; and

an electrical power source connected to said electrode layers for applying an electric field to alter the optical appearance of the cell.