Diaminomaleonitrile is also referred to as 2,3-diaminomaleonitrile and is the cis isomer as represented by the following formula. The trans isomer of this compound is called diaminofumazonitrile. The cis isomer is the common form and for convenience is referred to by the acronym DAMN. ##STR1## Although the starting geometry of DAMN is known to be “cis”, derivatives of DAMN do not necessarily retain the cis orientation. Background concerning DAMN and its cis and trans orientation and that of its derivatives can generally be found in U.S. Pat. No. 4,897,419 to Heidenreich et al. Along with Heidenreich et al, Begland et al in U.S. Pat. Nos. 3,912,724, 3,914,276, and 3,914,279 generally describe the use of .DAMN to synthesize aryl, cyclic, or heterocyclic molecules. For example, bis-anils of DAMN are prepared for use as dyes, for agricultural uses, and as toxins for pest control. Similar to Heidenreich and Begland, Japanese Patent No. 49-127921, disclosure dated Dec. 7, 1974, describes a method for preparing derivatives of DAMN which are salicylidenediaminomaleonitrile, 5-nitrofurfurylidenediaminomaleonitrile, nicotinylidenediaminomaleonitrile, and hexylidenediaminomaleonitrile. These compounds are described as being generally useful as agricultural chemicals. Formation of polymers based on DAMN derivatives is not reported.
In the past, polymers were not known for having good structural thermal stability and low volatility of decomposition products. Many polymers are difficult to make and difficult to use due to the complex nature of the starting materials, reaction processes, and the relative insolubility and/or infusible nature of such polymers rendering them difficult to coat. Currently used flame retardants often rely on additives which contain environmentally undesirable elements, such as halogens. Therefore, it is preferred to have a flame resistant material which is relatively easy to manufacture and coat.
Presently, there is a need for materials with high thermal stability for use under extreme service conditions. There is also a need for improved materials having desired thermal insulation characteristics, and structural thermal set plastics with high flame resistance. Therefore, what is needed is a new class of compounds and polymers formed therefrom, and a new method for their preparation. What is also needed are materials which have relatively low hydrogen content, relatively high nitrogen content, high thermal stability, low flammability, and a high char yield upon pyrolysis, rendering them useful for a variety of applications.
The invention provides a compound having conjugated double bonds in an acyclic structure formed by Schiff base reaction between an unsaturated aldehyde (RCHO) and diaminomaleonitrile (DE). The compound is a monoalkylated DAMN derivative having one unit of diaminomaleonitrile for every unit of alkyl (RC) derived from the unsaturated aldehyde. The invention also provides a polymer having an acyclic structure and containing monomeric units formed by Schiff base reaction between an unsaturated aldehyde and a diaminomaleonitrile.