Light modulating device having a silicon-containing matrix

• US 5,585,035 A
• Filed: 08/06/1993
• Issued: 12/17/1996
• Est. Priority Date: 08/06/1993
• Status: Expired due to Fees

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Nerad, Bruce A., Vesley, George F.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/103,271
• Time in Patent Office: 1,229 Days
• Field of Search: 252/299.01, 252/299.5, 428/1, 359/52
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: C09K 2323/053 Organic silicon compound, e.g. organosilicon

Abstract

In one aspect, an optically responsive film in which liquid crystal is dispersed in a matrix that includes siloxane linkages. The film has a transmissivity at -20° C. that is substantially the same as the transmissivity at 20° C. and a V₉₀ at -20° C. that is less than twice the value at 20° C.

In another aspect, an optically responsive film in which liquid crystal is dispersed in a matrix that includes the polymerization product of at least one mercapto-functional siloxane.

In another aspect, an optically responsive film in which liquid crystal is dispersed in a matrix that includes the polymerization product of at least one multi-functional ene and at least one multi-functional silicon hydride.

In another aspect, an optically responsive film in which liquid crystal is dispersed in a matrix that includes the reaction product of at least one multi-functional vinyl silane and at least one multi-functional thiol.

Claims

1. An optically responsive film comprising liquid crystal dispersed in a polymer matrix comprising siloxane linkages,

said film comprising the reaction product of at least one multi-functional siloxane-containing reactant in which the functional groups of said reactant are at least three carbon atoms away from the silicon atom,

said film having a transmissivity at -20°

C. that is substantially the same as the transmissivity of said film at 20°

C. and a V₉₀ at -20°

C. that is less than twice the value at 20°

C.

2. An optically responsive film comprising liquid crystal dispersed in a polymer matrix comprising siloxane linkages,

said film comprising the reaction product of at least one vinyl-functional siloxane having the general formula [CH₂ ═

CH]_x R_3-x SiOSiR_3-y [CH═

CH₂ ]_y where the sum x and y is between 2and 6, inclusive, and R is phenyl or a lower alkyl group,

said film having a transmissivity at -20°

C. that is substantially the same as the transmissivity of said film at 20°

C. and a V₉₀ at -20°

C. that is less than twice the value at 20°

C.

3. The optically responsive film of claim 2 wherein at least one of said vinyl-functional siloxanes comprises 1,3-divinyltetramethyldisiloxane;

1,3-divinyl-1,3-diphenyldimethyldisiloxane;

1,1,3,3-tetravinyldimethyldisiloxane;

or 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane.

4. An optically responsive film comprising liquid crystal dispersed in a polymer matrix that comprises the polymerization product of at least one multi-functional vinyl silane and at least one multi-functional thiol.

5. The optically responsive film of claim 4 wherein the stoichiometric ratio of thiol to vinyl silane ranges from about 0.5 to 3.0.

6. The optically responsive film of claim 4 wherein the stoichiometric ratio of thiol to vinyl silane is about 1.0.

7. The optically responsive film of claim 4 wherein at least one of said vinyl silanes has the general formula [CH₂ ═

CH]_n SiR_4-n where n is an integer between 2 and 4, inclusive, and R is phenyl or a lower alkyl group.

8. The optically responsive film of claim 7 wherein said vinyl silane comprises trivinylmethylsilane, divinyldimethylsilane, divinyldiphenylsilane, or tetravinylsilane.

9. The optically responsive film of claim 4 wherein at least one of said vinyl silanes is a vinyl siloxane having the general formula [CH₂ ═

CH]_x R_3-x SiOSiR_3-y [CH--CH₂ ]_y where the sum of x and y is between 2 and 6, inclusive, and R is phenyl or a lower alkyl group.

10. The optically responsive film of claim 9 wherein said vinyl silane comprises 1,3-divinyltetramethyldisiloxane;

1,3-divinyl-1,3-diphenyldimethyldisiloxane;

or 1,1,3,3-tetravinyldimethyldisiloxane.

11. The optically responsive film of claim 4 wherein at least one of said vinyl silanes is a cyclic vinyl siloxane having the general formula [[CH₂ ═

CH]_x R_2-x --SiO]_y where x is greater than zero but less than or equal to 2, y is between 3 and 6, inclusive, and R is phenyl or a lower alkyl group.

12. The optically responsive film of claim 11 wherein at least one of said vinyl silanes comprises 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane.

13. The optically responsive film of claim 4 wherein at least one of said multi-functional thiols has the general formula Z[OCO(CH₂)_n SH]_m where Z is a polyvalent organic moiety which is a CH_0-3 group-containing nucleus of a tri- or tetravalent alcohol of the type of glycerol or pentaerythritol, m is 3 or 4, and n is an integer between 1 and 5, inclusive.

14. The optically responsive film of claim 4 wherein at least one of said thiols comprises trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetrakis(3-mercaptopropionate).

15. The optically responsive film of claim 4 wherein at least one of said thiols comprises a mercapto-functional siloxane.

16. The optically responsive film of claim 15 wherein said thiol comprises (a) poly(3-mercaptopropylmethylsiloxane), or oligomers or copolymers thereof, or (b) 1,1,3,3-tetramethyl-1,3-bis(3-mercaptopropyl)disiloxane.

17. The optically responsive film of claim 4 wherein said matrix comprises the polymerization product of at least one multi-functional vinyl silane, at least one multi-functional thiol, and at least one mono-functional reactant.

18. The optically responsive film of claim 17 wherein said mono-functional reactant comprises a mono-functional allyl, acrylate, methacrylate, acrylamide, methacrylamide, thiol, vinyl silane, silicon hydride, or combination thereof.

19. The optically responsive film of claim 4 wherein said matrix comprises the reaction product of at least one multi-functional vinyl silane, at least one multi-functional thiol, and at least one multi-functional reactant different from said vinyl silane and said thiol.

20. The optically responsive film of claim 19 wherein said multi-functional reactant comprises a multi-functional allyl, acrylate, methacrylate, acrylamide, methacrylamide, silicon hydride, or combination thereof.

21. The optically responsive film of claim 4 wherein said liquid crystal is in the form of discrete droplets dispersed throughout the matrix.

22. The optically responsive film of claim 4 wherein the size of said liquid crystal droplets ranges from about 0.1 to 10 times the wavelength of light to be scattered.

23. The optically responsive film of claim 4 wherein said film comprises the ultraviolet-radiation cured polymerization product of said vinyl silane and said thiol.

24. The optically responsive film of claim 4 wherein said film comprises the thermally cured polymerization product of said vinyl silane and said thiol.

25. The optically responsive film of claim 4 wherein said film has a transmissivity at -20°

C. that is substantially the same as the transmissivity of said film at 20°

C. and a V₉₀ at -20°

C. that is less than twice the value at 20°

C.

26. A light modulating device comprising an optically responsive film to which an electric field is applied through a pair of electrodes,

said optically responsive film comprising liquid crystal dispersed in a matrix that comprises the polymerization product of at least one multi-functional vinyl silane and at least one multi-functional thiol.