Thermally Stable Spiropolymers

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Abstract
The condensation of the aliphatic spirotetraamine 2,2-bis(aminomethyl)-1,3-diaminopropane (I) or 1,4-bis(aminomethyl)-1,4-diaminocyclohexane (II) with pyromellitic dianhydride (III) or 1,4,5,8-naphthalenetetracar-boxylic dianhydride (IV) was studied. It was found that in polyphos-phoric acid at temperatures greater than 200°C and after long reaction times, either tetraamine produced the desired spiropolymer with the dianhydride (IV), but only tars could be isolated when the dianhydride (III) was used. Although these condensations proceed through a polyimide precursor which then cyclizes by elimination of water, condensations of (II) with (IV) only yielded the fully cyclized material and all attempts to isolate the imide precursor failed. Strong evidence for total cyclization was obtained by comparing the infrared and ultraviolet spectra of the polymer and of model compounds that were representative of the fully cyclized and imide forms. Condensations of (I) and (IV) yielded polymers that were only 50% cyclized. The polymer based on spirotetraamine (I) started to lose weight at 300°C in both air and vacuum, while the polymer based on amine (II) showed no weight loss until 500 C in vacuum and 400°C in air.

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