Liquid crystal droplets dispersed in thin films of UV-curable polymers

• US 4,728,547 A
• Filed: 11/21/1986
• Issued: 03/01/1988
• Est. Priority Date: 06/10/1985
• Status: Expired due to Term

• Current Assignee: Brown University
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Smith, George W., Vaz, Nuno A.
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US06/933,212
• Time in Patent Office: 466 Days
• Field of Search: 427/54.1, 428/1, 128/736, 350/331 R, 350/351, 252/299.66
• US Class Current: 349/16
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals

Abstract

Optically responsive films comprising birefringent nematic and/or birefringent chiral nematic liquid crystal microdroplets dispersed in UV-cured polymeric reaction products of di- and/or triallyl ethers and esters and suitable polythiols are disclosed.

Claims

1. An optically responsive film comprising birefringent nematic and/or brirefringent chiral nematic liquid crystal microdroplets dispersed in a film of the ultraviolet radiation cured reaction product of a polyallyl compound and a polythiol taken from the group consisting of Z[OCO(CH₂)_n SH]_m, where Z=a polyvalent organic moiety which is the CH_0-3 group containing nucleus of a tri- or tetravalent alcohol of the type of glycerol or pentaerythritol, m=3 or 4and n=1 to 5, said microdroplets displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy, said film being capable of undergoing repeated thermally and electrically or magnetically induced transitions between opaque and transparent.

2. An optically responsive film comprising birefringent nematic and/or birefringent chiral nematic liquid crystal microdroplets dispersed in a film of the ultraviolet radiation cured reaction product of triallyl isocyanurate and pentaerythritol tetakis(3-mercapto-propionate), said microdroplets displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy, said film being capable of undergoing repeated thermally and electrically or magnetically induced transitions between opaque and transparent.

3. A method of making an optically responsive film containing microdroplets of a birefringent nematic and/or birefringent chiral nematic liquid crystal material dispersed in a polymer film comprising

mixing a liquid crystal material with the UV-curable liquid precursor mixture comprising a polyallyl compound and a polythiol taken from the group consisting of Z[OCO(CH₂)_n SH]_m, where Z=a polyvalent organic moiety which is the CH_0-3 group containing nucleus of a tri- or tetravalent alcohol of the type of glycerol or pentaerythritol, m=3 or 4and n=1 to 5, and thereafter

curing the mixture in the form of a film with high intensity ultraviolet radiation to thereby form a cured polymer matrix which is a reaction product of said allyl compound and polythiol containing dispersed therein droplets of liquid crystal material displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy.

4. A method of making an optically responsive film containing microdroplets of a birefringent nematic and/or birefringent chiral nematic liquid crystal material dispersed in a polymer film comprising

mixing a liquid crystal material with the UV-curable liquid precursor mixture comprising triallyl isocyanurate and pentaerythritol tetrakis(3-mercapto-propionate) and thereafter

curing the mixture in the form of a film with high intensity ultraviolet radiation to thereby form a cured polymer matrix which is a reaction product of said precursors containing dispersed therein droplets of liquid crystal material displaying positive dielectric anistropy and/or positive diamagnetic anisotropy.