Polymer liquid crystal emulsion stabilized by water soluble copolymer, liquid crystal composite film and method for preparing thereof

• US 6,270,691 B2
• Filed: 02/26/1999
• Issued: 08/07/2001
• Est. Priority Date: 10/28/1998
• Status: Expired due to Fees

• Current Assignee: Korea Research Institute of Chemical Technology
• Original Assignee: Korea Research Institute of Chemical Technology
• Inventors: Kim, Mun-Han, Park, Soo-Jin, Lee, Jae-Rock
• Primary Examiner(s): Kelly, C. H.
• Application Number:
  US09/258,346
• Publication Number:
  US 20010001480A1
• Time in Patent Office: 893 Days
• Field of Search: 252/299.01, 252/299.5
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/542 Macromolecular compounds
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal

Abstract

A polymer liquid crystal emulsion includes a liquid crystal and a water soluble copolymer obtained by polymerizing a hydrophilic monomer with one or more hydrophobic monomers. The concentration of the hydrophobic monomer may be 14 to 25% by weight based on the combined weight of the hydrophobic monomer and the hydrophilic monomer. The hydrophobic monomer may be styrene, methyl methacrylate, vinyl acetate, acrylate or methacrylate. The hydrophilic monomer may be acrylamide, acrylonitrile or acryloylchloride. Preferably, the hydrophilic monomer is acrylamide or a derivative thereof and the hydrophobic monomer is styrene, methyl methacrylate or vinyl acetate. The liquid crystal may be a nematic liquid crystal formed of an azomethine compound or an azo compound. The water soluble copolymer, the liquid crystal and water may form a liquid crystal/aqueous polymer solution. In this case, the concentration of the liquid crystal in the liquid crystal/aqueous polymer solution is in the range of 50 to 70% by weight. A nematic curvilinear alignment phase film may be formed from the polymer liquid crystal emulsion and a pair of plates sandwiching the polymer liquid crystal emulsion.

Claims

1. A polymer liquid crystal emulsion, comprising:

a water soluble copolymer obtained by nematic curvilinear aligned phase polymerization of a hydrophilic monomer with one or more hydrophobic monomers, the content of the one or more hydrophobic monomers being 14 to 25% by weight based on the combined weight of the one or more hydrophobic monomers and the hydrophilic monomer; and

a liquid crystal, the polymer liquid crystal emulsion containing substantially no dispersion agents.

2. A polymer liquid crystal emulsion according to claim 1, wherein said hydrophilic monomer is acrylamide or a derivative thereof and said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate and vinyl acetate.

3. A polymer liquid crystal emulsion according to claim 1, wherein said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate, vinyl acetate, acrylate and methacrylate.

4. A polymer liquid crystal emulsion according to claim 1, wherein said hydrophilic monomer is selected from the group consisting of acrylamide, acrylonitrile and acryloylchloride.

5. A polymer liquid crystal emulsion according to claim 1, wherein

the water soluble copolymer, the liquid crystal and water form a liquid crystal/aqueous polymer solution, and

the concentration of the liquid crystal in the liquid crystal/aqueous polymer solution is in the range of 50 to 70% by weight.

6. A polymer liquid crystal emulsion according to claim 1, wherein said liquid crystal is a nematic liquid crystal formed of an azomethine compound or an azo compound.

7. A sandwiched nematic curvilinear alignment phase film, comprising:

a polymer liquid crystal emulsion having;

a water soluble copolymer obtained by nematic curvilinear aligned phase polymerization of a hydrophilic monomer with one or more hydrophobic monomers, the content of the one or more hydrophobic monomers being 14 to 25% by weight based on the combined weight of the one or more hydrophobic monomers and the hydrophilic monomer; and

a liquid crystal; and

a pair of plates sandwiching the polymer liquid crystal emulsion, the sandwiched nematic curvilinear alignment phase film containing substantially no dispersion agents.

8. A sandwiched nematic curvilinear alignment phase film according to claim 7, wherein said hydrophilic monomer is acrylamide or a derivative thereof and said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate and vinyl acetate.

9. A sandwiched nematic curvilinear alignment phase film according to claim 7, wherein said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate, vinyl acetate, acrylate and methacrylate.

10. A sandwiched nematic curvilinear alignment phase film according to claim 7, wherein said hydrophilic monomer is selected from the group consisting of acrylamide, acrylonitrile and acryloylchloride.

11. A sandwiched nematic curvilinear alignment phase film according to claim 7, wherein

the water soluble copolymer, the liquid crystal and water form a liquid crystal/aqueous polymer solution, and

the concentration of the liquid crystal in the liquid crystal/aqueous polymer solution is in the range of 50 to 70% by weight.

12. A sandwiched nematic curvilinear alignment phase film according to claim 7, wherein said liquid crystal is a nematic liquid crystal formed of an azomethine compound or an azo compound.

13. A method for producing a nematic curvilinear alignment phase film, comprising the following steps:

a) conducting nematic curvilinear aligned phase polymerization of a hydrophilic monomer with one or more hydrophobic monomers to form a water soluble copolymer, the content of the one or more hydrophobic monomers being 14 to 25% by weight based on the combined weight of the one or more hydrophobic monomers and the hydrophilic monomer;

b) washing and drying the water soluble copolymer and then dissolving the water soluble copolymer in water to form a solution;

c) dispersing a liquid crystal into the solution to produce a liquid crystal/polymer aqueous solution; and

d) placing the liquid crystal/polymer aqueous solution between glass substrates in order to remove water therefrom, the nematic curvilinear alignment phase film being produced with substantially no dispersion agents.

14. A method for producing a nematic curvilinear alignment phase film according to claim 13, wherein said hydrophilic monomer is acrylamide or a derivative thereof and said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate and vinyl acetate.

15. A method for producing a nematic curvilinear alignment phase film according to claim 13 wherein said hydrophobic monomer is selected from the group consisting of styrene, methyl methacrylate, vinyl acetate, acrylate and methacrylate.

16. A method for producing a nematic curvilinear alignment phase film according to claim 13, wherein said hydrophilic monomer is selected from the group consisting of acrylamide, acrylonitrile and acryloylchloride.

17. A method for producing a nematic curvilinear alignment phase film according to claim 13, wherein

the water soluble copolymer, the liquid crystal and water form a liquid crystal/aqueous polymer solution, and

the concentration of the liquid crystal in the liquid crystal/aqueous polymer solution is in the range of 50 to 70% by weight.

18. A method for producing a nematic curvilinear alignment phase film according to claim 13, wherein said liquid crystal is a nematic liquid crystal of azomethine compounds or azo compounds.

19. A method for producing a nematic curvilinear alignment phase film according to claim 13, wherein the content of the hydrophobic monomer is 14 to 25% by weight based on the combined weight of the hydrophobic monomer and the hydrophillic monomer.