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Magnetic Liquid Crystalline Compositions

IP.com Disclosure Number: IPCOM000073641D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

O'Hern, RJ: AUTHOR [+2]

Abstract

Magnetic liquid crystalline compositions are produced by coating magnetic compounds with liquid crystalline materials. Before coating, magnetic particles, such as iron, cobalt, nickel, or magnetic oxides thereof, are first degassed. Degassing is provided by subjecting the particles to a high vacuum, preferably with heating. The degassed particles can then be coated with liquid crystalline material while still under vacuum.

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Magnetic Liquid Crystalline Compositions

Magnetic liquid crystalline compositions are produced by coating magnetic compounds with liquid crystalline materials. Before coating, magnetic particles, such as iron, cobalt, nickel, or magnetic oxides thereof, are first degassed. Degassing is provided by subjecting the particles to a high vacuum, preferably with heating. The degassed particles can then be coated with liquid crystalline material while still under vacuum.

For example, iron oxide is degassed in a high vacuum chamber at approximately 10-5 torr. while heating at 140 degrees C for one hour. After degassing is completed, the temperature is lowered to 100 degrees C while maintaining the vacuum. Liquid crystalline material, such as cholesteryl n- propionate, is then inserted into the chamber and mechanically mixed with the degassed iron oxide. The liquid crystalline material melts around the warm iron oxide. After mixing is completed, the mixture is allowed to cool, and the pressure is returned to atmospheric. The coated particles are a magnetic liquid crystalline material.

For ease of handling, the resulting coated particles are then dispersed in a suitable carrier, such as methyl phenyl silicone. This dispersion responds optically as a mesophase to a magnetic field under ambient conditions. As temperature is increased, optical response is also increased. Magnetic liquid crystalline compositions are useful as a storage medium for magneto-optic readout or as a d...