SynopsisSynthesis of the first totally organic spiro polymer was accomplished by the reaction of 1,bcyclohexanedione and pentaerythritol in benzene plus a trace of ptoluenesulfonic acid to produce the polyspiroketal. The polymer did not melt, but began to decompose at 350°C. Although it was insoluble in most common solvents, it was found to be soluble in hexafluoroisopropanol. The x-ray diffraction indicated the polymer was very highly crystalline. A series of lower molecular weight related polymers were prepared by carrying out a similar condensation with a mixture of 1,bcyclohexanedione containing 5-50 mole-% of cyclohexanone. In order to prepare a material with greater solubility, a polyspiroketal was prepared from 1,lO-cyclooctadecanedione plus pentaerythritol. This polymer was soluble not only in hexafluoroisopropanol, but to a limited extent in dimethyl sulfoxide.

Polycondensation of several aliphatic and fluorine-containing, aromatic diamines with two isomeric aromatic diketones has been accomplished by means of acid-catalyzed solution polymerizations. The three polymeric products were semiaromatic or completely aromatic depending upon the diketone-diamine combination employed. Comparative thermal stabilities of the products both in air and in an inert atmosphere were investigated by thermogravimetric analysis. The completely aromatic, fluorine-containing polymers exhibited a high degree of thermal stability and all three of the polymers synthesized exhibited the surprising property of essentially the same resistance to initial thermal decomposition in the oxidative as well as the inert atmosphere. Three isomeric polymers synthesized in a previous investigation by the acid-catalyzed polycondensation of mdibenzoylbenzene with the three phenylenediamines were subjected to thermogravimetric analysis after which the condensable volatiles were collected and then analyzed by combined vapor phase chromatography and mass spectroscopy. Separation and identification of the products given off upon thermal degradation by this combined analytical technique has indicated that different mechanisms are operative in the thermal decomposition of these isomeric polymers. PolymericSchiff bases synthesized from dialdehydes and aromatic diamines have been reported by several investigators to exhibit a high resistance to thermal stress.2-5 However, there are very few examples reported in the literature in which a diketone is used as the starting dicarbonyl.6,7 We have, therefore, undertaken to synthesize and characterize the thermal behavior of a series of polymers based upon the condensation polymerization of various aliphatic and aromatic diamines with several isomeric aromatic diketones. The polymers obtained varied in molecular structure since their backbones ranged from semiaromatic to completely aromatic depending upon the starting diketone-diamine combination employed.Three polymers were synthesized by the acid-catalyzed polycondensation of w-dibenzoylbenzene with ethylenediamine, and by the polycondensation of /7-dibenzoylbenzene with tetrafluoro-m-phenylenediamine and tetrafluoro-p-phenylenediamine. The thermal stability of these polymers was determined by thermogravimetric analysis in air and in an inert atmosphere. In addition, three isomeric polymers which were synthesized in a previous investigation8 by the polycondensation of 7?7-dibenzoylbenzene with o-, m-, and /7-phenylenediamine were subjected to combined thermogravimetric analysis (tga)-vapor phase chromatography (vpc)mass spectral analysis (ms). By means of this combined analysis, it was possible to degrade thermally a polymer (1) To whom correspondence should be addressed.(2) A.

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Since the study of model compounds had shown that ketals containing five-, six-, seven-, and eight-membered rings could be formed in very high yields by heating a ketone or diketone with a diol in the presence of an acid catalyst with removal of the water that was formed by azeotropic distillation, these reactions were extended to produce a series of new analogous polyspiroketals. Furthermore since the formation of the intermediate hemiketal is not a stable product and it is necessary to proceed all the way to the ketal before a stable unit is formed, this reaction appeared ideal for the synthesis of soluble linear polyspiroketals containing only cyclicized structures. This reaction also represents a condensation polymerization analog of the free radical inter-intramolecular polymerization to produce linear polymers. Thus it was shown that linear soluble polymers could be prepared from the following polyfunctional materials: a five-membered ring -containing polyketal from 1,2,4,5-tetrahydroxy-cyclohexane and 1,4-cyclohexanedione; six-membered ring-containing polyketal from 1,1,4,4-tetrakis(hydroxymethyl)cyclohexane, and 1,1,6,6-tetrakis(hydroxymethyl) cyclohexanone; six-membered ring-containing polyketal from 1,3-dihydroxyacetone, as well as 1,10-cyclooctadecanedione and pentaerythritol; a seven-membered ring -containing polyketal from 1,4-cyclohexanedione and 1,2,4,5-tetrakis(hydroxymethy1)-