Non-lithographic photo-induced patterning of polymers from liquid crystal solvents with spatially modulated director fields

• US 7,372,480 B1
• Filed: 12/07/2004
• Issued: 05/13/2008
• Est. Priority Date: 09/27/2000
• Status: Expired due to Fees

• Current Assignee: Kent State University
• Original Assignee: Kent State University
• Inventors: Shiyanovskii, Sergij, Voloschenko, Dmitry, Lavrentovich, Oleg D.
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US11/005,779
• Time in Patent Office: 1,253 Days
• Field of Search: 348/51, 348/55, 348/88, 359462-464
• US Class Current: 348/88
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 2201/305 diffraction grating

Abstract

A liquid crystal device comprises a first and second cell wall structure; at least one liquid crystal material disposed within a space between the first and second cell wall structures; and polymer micro-structures, wherein the micro-structures are formed by polymerizing a prepolymer, and wherein said micro-structures have a shape and spatial location determined by said liquid crystal material. Permanent polymer micro-structures are formed from a liquid crystal with a non-uniform spatially modulated director field. The polymer structures have the shape and spatial location dictated by the non-uniform director field of the liquid crystal. The micro-structures are a backbone that restores the liquid crystal director field that existed during the polymerization process even when other factors, such as electric field, temperature, or surface anchoring, do not favor this restoration. The polymer micro-structures can be used in optical devices, such as diffraction gratings and deflecting and beam steering devices, and in micro-mechanical and micro-fluidic devices.

Claims

1. A liquid crystal device comprising:

a pair of opposed substrates having a gap therebetween;

a liquid crystal material disposed in said gap; and

polymer micro-structures formed between said substrates, wherein the micro-structures are formed by causing the liquid crystal material to assume a predetermined orientation with non-uniform spatially modulated director and thereafter polymerizing a prepolymer, and wherein the micro-structures have a shape and spatial location determined by a director field of said liquid crystal material.

2. A liquid crystal device according to claim 1, wherein said micro-structures are affixed to said at least one of the substrates.

3. A liquid crystal device according to claim 1, additionally comprising an alignment layer disposed on at least one of said substrates.

4. A liquid crystal device according to claim 3, wherein said alignment layer is selected from the group consisting of polymers, silicon oxide layers and surfactants.

5. A liquid crystal device according to claim 3, wherein said alignment layer produces a homogeneous planar geometry of the director field.

6. A liquid crystal device according to claim 3, wherein said alignment layer produces a homogeneous tilted geometry of the director field.

7. A liquid crystal device according to claim 3, wherein said alignment layer produces a homeotropic geometry of the director field.

8. A liquid crystal device according to claim 3, wherein said alignment layer produces a patterned geometry of the director field with different alignment properties at different regions of the cell.

9. A liquid crystal device according to claim 1, wherein said liquid crystal material is selected from the group consisting of nematic liquid crystal material, cholesteric liquid crystal material, smectic liquid crystal material and columnar liquid crystal material.

10. A liquid crystal device according to claim 1, wherein said prepolymer is selected from the group consisting of UV-curable prepolymers and heat-curable prepolymers.