Poly parabanic acids

Poly(iminoimidazolidinediones) are produced from diisocyanates and HCN, and these hydrolyze to polyparabanic acids  

Poly(parabanic acids) are amorphous, unbranched thermoplasts. According to the nature of R (aromatic, aliphatic, alicyclic), the softening points of these polymers lie between room temperature and 300°C. The mechanical properties of the polymers are quite good, but the water uptake is relatively high. 

Closely related to the polyhydantoins are the 2,4,5-triketoimidazolidine polymers, known as poly(parabanic acids) and produced by Exxon (Tradlon) and Hoechst. They contain the basic structure 

Materials of these types have TgS of some 290-300°C and some grades are claimed to be stable to about 400°C. Whilst resistant to hydrocarbons, halogenated hydrocarbons, ethers and acids the polymers are soluble in such materials as dimethylformamide, N-methylpyrrolidone and pyridine. Bases can cause stress cracking. These non-crystalline polymers are tough at temperatures as low as -46°C whilst at 260°C they have the strength shown by PTFE at room temperature. The polymers also exhibit excellent electrical insulation properties. 

Fabrication is most conveniently carried from solution to produce insulating film, wire lacquers and even fibres. The polymers have also been compression moulded. Some properties of two experimental Exxon grades are given in Table 21.8. 

The polymers considered in this chapter have the common feature of possessing in-chain rings which give them higher TgS than their aliphatic counterparts and even their ortho- and meta-analogues. In themselves they divide into three groups  

WRIGHT, w. w., and lee, w. a., The Search for Theimally Stable Polymers , Chapter in Progress in High Polymers Vol. II (Eds. robe and peaker, Heywood, London (1968) 

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Table 21.8 Some properties of compression moulded poly(parabanic acid) materials at 23°C22...

For a poly(parabanic acid) resin as substrate, a6T as semiconductor, and cyanoethylpullulan, a highly flexible device could be obtained which shows no changes in the transistor characteristic after bending and twisting. However, the metallic gate and source electrodes sometimes disconnect. A really pure all-organic FET with a graphite-based polymer ink used to prepare the source and drain contacts does not even show this instability [305],... 

Poly(parabanic acids) are close relatives of poly(hydantoins). They are also known as 2,4,5-triketoimidazolidine polymers. They can be produced by several processes, for example, from oxamidic esters and (capped) isocyanates ... 

Poly(parabanic acids) are amorphous polymers that can be processed to films, coatings, and isolation material by film casting or compression molding. Solutions in, for example, N-methyl pyrrolidone are suitable as cable lacquers or adhesives. 

J. P. Luongo and H. Schornhorn, Thermal Degradation of Poly(parabanic acid), J. Polym. Sci. (Chem.) 13, 1363 (1975). 

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