Polymer dispersed liquid crystals in radiation curable electron-rich alkene-thiol polymer mixtures

A radiation curable polymerizable mixture comprising:

• a multifunctional thiol.
• at least one multifunctional electron-rich alkene which does not undergo appreciable homo polymerization and is selected from the group consisting of:
• (a) vinyl ethers and vinyl sulfides;
• (b) keteneacetals, ketenethioacetals and methylene oxathiolanes wherein the carbon of the carbon-carbon double bond not bearing the electron donating group, has bonded to it H or a combination of H and a C.sub.1 to C.sub.6 alkyl;
• (c) ortho or para vinyl phenyl ethers or thioethers;
• and
• (d) bicylic alkenes which have as a result of their stereoelectronic configuration unequal .pi.-electron density above and below the plane of the carbon-carbon double bond axis,
• a photoinitiator, and
• a liquid crystal material soluble in said polymerizable mixture in an amount of between about 20 and about 90% by weight of the mixture, said liquid crystal having a molecular weight of less than 1000, wherein
• the total reacting functionality of the mixture being greater than 4 and the ratio of equivalents of thiol to electron-rich alkene component being from about 0.5;1 to about 2.0:1, and wherein after 100 milliseconds the fraction of the initial voltage sufficient to make a film of the cured mixture clear and transparent, remaining on a pixel element, is 0.82 or higher.