Akzo Nobel N.v.

Akzo N.v.

Erwin W Erdhuisen

Paulus Pieter De Wit

Carel T Wreesmann

John Griffiths

Doetze J Sikkema

Kasali A Bello

Johan B Reesink

Disclosed are liquid-crystalline and infrared-sensitive liquid-crystalline polyesters for optical data storage, processes for the preparation of the same, and an apparatus comprising an infrared-sensitive liquid-crystalline polyester. Owing to covalently bonded dye the liquid crystalline polyester is infrared sensitive and high concentrations of dye are obtainable, without having detrimental effects on the properties of the liquid-crystalline polyester. This results in a highly sensitive liquid-crystalline polyester for optical data storage. Infrared dyes which are preferably bonded in liquid-crystalline polyester are croconium, squarilium, azo, and azamethine dyes.

Liquid crystalline and infrared-sensitive liquid-crystalline polyesters

The invention is in the field of intrinsically thermochromic material. We have found that infrared absorbing dyes of the azamethine type have intrinsically thermochromic properties. The use of said dyes as thermochromic material has the advantage that they can be thermally activated by infrared irradiation. Irradiation of such material with a laser causes a color change that can be used in imaging and optical data storage. The thermochromic dyes can be mixed with polymeric material and from the resulting polymer composition films can be made. If the dye contains polymerizable groups, it may be covalently incorporated into the polymer.

Thermochromic infrared dyes

The invention relates to a liquid-crystalline polyurethane having a side chain comprising a mesogenic group, giving a clear polyurethane which does not isomerize under the influence of light. Such liquid-crystalline polyurethanes are highly suited to be used for optical data storage. The invention further relates to infrared-sensitive liquid-crystalline polyurethanes and liquid-crystalline polyurethane compositions, films containing said liquid-crystalline polyurethanes or polyurethane compositions, and a device for optical data storage containing said liquid-crystalline polyurethanes or polyurethane compositions.

Liquid-crystalline polyurethanes, compositions of said

Polyurethanes having high hyperpolarizability densities and other favorable properties can be easily prepared from nonlinear optical active diols (NLO-diols) of a certain general formula, which have a delocalized .pi. electron system to which both an electron donor group and an electron acceptor group are coupled directly (D.pi.A system). The polyurethanes may be used in optical waveguides.

Non-linear optical active diols and polyurethanes prepared therefrom

A linear addition polymer having sidegroups which may be coupled to it or not through a spacer and have a molecular hyperpolarizability .beta. of at least 10.sup.-38 m.sup.4 /V, characterized in that the recurring units of the polymer correspond to the formula ##STR1## wherein X represents a hydrogen atom or a lower alkyl group and m=1 or optionally 0, where

Linear addition polymer with hyperpolarizable side groups

Liquid crystalline side-chain polyesters prepared by polycondensing a dicarboxylic acid or a derivative thereof with a diol of a certain general formula. Of such diols the essence is that they have a delocalized .pi. electron system to which both an electron donor group and an electron acceptor group are coupled directly (D.pi.A-system). Because of the structure of the diol to which the D.pi.A-system is linked the polyesters exhibit excellent Tg and Tc values. The polyesters are to be used in optical waveguides or for optical data storage.

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Duiven, Netherlands

Erwin W Erdhuisen