Synthesis and characterization of the t-butyl ester of the oxydianiline/pyromellitic dianhydride polyamic acid.

Novel t-butyl esters of oxydianiline/pyromellitic dianhydride polyamic acid were prepared in good yield with high molecular weights. The polymers were prepared with either meta or para repeating units. The cure behavior of these t-butyl esters was studied by IR, MS, and TG analysis and was compared to that of both the parent polyamic acid and its methyl ester. It was found that a rapid deprotection of the t-buytyl group occurs at around 200C with liberation of free polyamic acid. Consequently, the cure behavior at 200C of the T-butyl ester approaches that of the parent polyaymic acid. Furthermore, the isomerism of the repeating units does not appear to have any detectable effect on the cure behavior of the polymer, although, meta isomerism appears to enhance solubility of the polymer in organic solvents.