Thermotropic chiral nematic liquid crystalline copolymers

• US 5,332,522 A
• Filed: 04/29/1993
• Issued: 07/26/1994
• Est. Priority Date: 04/29/1993
• Status: Expired due to Fees

• Current Assignee: University of Rochester
• Original Assignee: University of Rochester
• Inventors: Krishnamurthy, Sushil, Mastrangelo, John C., Shi, Hongqin, Chen, Shaw H.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/055,120
• Time in Patent Office: 453 Days
• Field of Search: 252/299.01, 428/1, 359/36, 359/301, 359/318
• US Class Current: 252/299.01
• CPC Class Codes: C08F 220/303 and one or more carboxylic moieties in the chain
• CPC Class Codes: C08F 220/365 containing further carboxylic moieties
• CPC Class Codes: C09K 19/3852 Poly(meth)acrylate derivatives
• CPC Class Codes: C09K 19/3857 containing at least one asymmetric carbon atom

Abstract

A thermotropic chiral nematic liquid crystalline copolymer composition comprises ##STR1## wherein --NEM-- and --NEM'"'"'-- are each independently nematogenic units of formula ##STR2## wherein R is H or CH₃, --Q-- is an alkylene radical having 1 to about 8 carbon atoms,

--X-- is --O--, --S--, or --CH₂ --, --Y-- is ##STR3## --Z is --CN, --NO₂ or --N═C═S, q and r are each independently 0 or 1;

wherein --CHI-- is a chiral unit of formula ##STR4## wherein R is H or CH₃, --Q'"'"'-- is an alkylene radical having 1 to about 8 carbon atoms,

--X'"'"'-- is --O--, --S--, or --CH₂ --,

--Z'"'"' is an alkoxy, aralkoxy, alkylamino, or aralkylamino radical having 4 to about 12 carbon atoms and containing at least one asymmetric carbon atom,

q'"'"' and r'"'"' are each independently 0 or 1;

and wherein x is the mole fraction of chiral units and (y+y'"'"') is the total mole fraction of nematogenic units in said copolymer composition, and the ratio of x to (y+y'"'"') is from about 1:50 to 1:1.

This compolymer composition is employed to form an optical device.

Claims

1. A chiral nematic liquid crystalline copolymer composition comprised of the repeating units of formula ##STR39## wherein --NEM-- and --NEM'"'"'-- are each independently nematogenic units of formula ##STR40## wherein R is H or CH₃, --Q-- is an alkylene radical having 1 to about 8 carbon atoms,

--X-- is --O--, --S--, or --CH₂ --, --Y-- is ##STR41## --Z is --CN, --NO₂, or --N═

C═

S, q and r are each independently 0 or 1;

wherein --CHI-- is a chiral unit of formula ##STR42## wherein R is H or CH₃, --Q'"'"'-- is an alkylene radical having 1 to about 8 carbon atoms,

--X'"'"'-- is --O--, --S--, or --CH₂ --,

--Z'"'"' is an alkoxy, aralkoxy, alkylamino, or aralkylamino radical having 4 to about 12 carbon atoms and containing at least one asymmetric carbon atom,

q'"'"' and r'"'"' are each independently 0 or 1;

and wherein x is the mole fraction of chiral units, and (y+y'"'"') is the total mole fraction of nematogenic units in said copolymer composition, and the ratio of x to (y+y'"'"') is from about 1;

50 to 1;

1.

2. A composition of claim 1 wherein said ratio of x to (y+y'"'"') is from about 1:

20 to 1;

3.

3. A composition of claim 1 wherein said copolymer composition has a weight average molecular weight of about 1,500 to 50,000.

4. A composition of claim 3 wherein said weight average molecular weight is about 2,000 to 20,000.

5. A composition of claim 1 wherein --X-- is --O--, --Y-- is --C.tbd.C-- or p-phenylene, and q and r are each 1.

6. A composition of claim 5 wherein Q contains 3 to 6 carbon atoms and --Z is --CN.

7. A composition of claim 1 wherein --Z'"'"' is an alkoxy or aralkoxy radical derived from an alcohol.

8. A composition of claim 7 wherein said alcohol is 1-phenylethanol, 2-methoxy-2-phenylethanol, or mandelic acid methyl ester.

9. A composition of claim 1 wherein --Z'"'"' is an alkylamino or aralkylamino radical derived from an amine.

10. A composition of claim 9 wherein said amine is 1-phenylethylamine, 1-cyclohexylethylamine, or 3-amino-ε

-caprolactam.

11. A composition of claim 1 wherein said chiral unit --CHI-- has the formula ##STR43##

12. A composition of claim 1 wherein said chiral unit --CHI-- has the formula ##STR44##

13. A composition of claim 1 wherein said nematogenic unit --NEM-- has the formula ##STR45##

14. A composition of claim 1 wherein said nematogenic unit --NEM-- has the formula ##STR46##

15. A composition of claim 1 wherein said nematogenic unit --NEM-- has the formula ##STR47##

16. A composition of claim 1 having the formula ##STR48##

17. A composition of claim 1 having the formula ##STR49##

18. A composition of claim 1 having the formula ##STR50##

19. An optical device comprising an optically transparent substrate and a film formed from a chiral nematic liquid crystalline copolymer composition comprised of the repeating units of the formula ##STR51## wherein --NEM-- and --NEM'"'"'-- are each independently nematogenic units of formula ##STR52## wherein R is H or CH₃, --Q-- is an alkylene radical having 1 to about 8 carbon atoms,

--X-- is --O--, --S--, or --CH₂ --, --Y-- is ##STR53## --Z is --CN, --NO₂, or --N═

C═

S, q and r are each independently 0 or 1;

wherein --CHI-- is a chiral unit of formula ##STR54## wherein R is H or CH₃, --Q'"'"'-- is an alkylene radical having 1 to about 8 carbon atoms,

--X'"'"'-- is --O--, --S'"'"', or --CH₂ --,

--Z'"'"' is an alkoxy, aralkoxy, alkylamino, or aralkylamino radical having 4 to about 12 carbon atoms and containing at least one asymmetric carbon atom,

q'"'"' and r'"'"' are each independently 0 or 1;

and wherein x is the mole fraction of chiral units and (y+y'"'"') is the total mole fraction of nematogenic units in said copolymer composition, and the ratio of x to (y+y'"'"') is from about 1;

50 to 1;

1.

20. An optical device of claim 19 wherein said substrate is glass or fused quartz.

21. An optical device of claim 19 wherein said film has a thickness of about 0.5 μ

m to 50 μ

m.

22. An optical device of claim 21 wherein said thickness is about 5 μ

m to 20 μ

m.

23. An optical device of claim 19 wherein said copolymer composition has the formula ##STR55##

24. An optical device of claim 19 wherein said copolymer composition has the formula ##STR56##

25. An optical device of claim 19 wherein said copolymer composition has the formula ##STR57##