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

Claim 2

An optically-responsive film comprising liquid crystal microdroplets (14) dispersed in a polymer film, characterised in that the film (10) comprises an ultraviolet radiation-cured reaction product of triallyl isocyanurate and a polythiol taken from the group consisting of Z[OCO(CH 2 ) n SH] m , where Z = a polyvalent organic moiety which is the CH O-3 group-containing nucleus of a tri- or tetravalent alcohol such as glycerol or pentaerythritol, m = 3 or 4, and n = 1 to 5, said film (10) being capable of undergoing repeated thermally or electrically or magnetically- induced transitions between opaque and transparent.

Claim 3

An optically-responsive film according to Claim 1, comprising nematic, cholesteric and/or smectic liquid crystal microdroplets (14) dispersed in the polymer film (10), characterised in that the film (10) is the ultraviolet radiation-cured reaction product of triallyl isocyanurate and pentaerythritol tetrakis(2-mercapto-propanoate).

Claim 4

A method of making an optically-responsive film (10) containing microdroplets (14) of a liquid crystal material dispersed in a polymer film according to Claim 1, characterised in that the method includes the steps of mixing a liquid crystal material (14) with a UV-curable liquid precursor mixture comprising triallyl isocyanurate and a polythiol taken from the group consisting of Z[OCO(CH 2 ) n SH] m , where Z = a polyvalent organic moiety which is the CH 0-3 group-containing nucleus of a tri- or tetravalent alcohol such as glycerol or pentaerythritol, m = 3 or 4, and n = 1 to 5, and then letting the mixture stand, the time of mixing and the time of standing being determined so as to obtain a desired liquid crystal droplet size and size range in the final polymer matrix, and thereafter curing the mixture in the form of a film (10) with high intensity ultraviolet radiation to thereby form a cured polymer matrix (12) which is a reaction product of said isocyanurate and polythiol, said polymer matrix (12) containing dispersed therein said sized droplets (14) of liquid crystal material.

Claim 5

A method of making an optically-responsive film (10) containing microdroplets (14) of a liquid crystal material dispersed in a polymer film according to Claim 2, characterised in that the method includes the steps of mixing a liquid crystal material (14) with a UV-curable liquid precursor mixture comprising triallyl isocyanurate and pentaerythritol tetrakis(2-mercapto-propanoate) and then letting the mixture stand, the time of mixing and the time of standing being determined so as to obtain a desired liquid crystal droplet size and size range in the final polymer matrix, and thereafter curing the mixture in the form of a film (10) with high intensity ultraviolet radiation to thereby form a cured polymer matrix (12) which is a reaction product of said precursors, said polymer matrix (12) containing dispersed therein said sized droplets (14) of liquid crystal material.