Synthesis of Pyrrone Polymers.
WESTINGHOUSE RESEARCH LABS PITTSBURGH PA
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Several methods were found to control the gelation problem encountered in preparing pyrrones from dianhydrides and tetramines in polar solvents. Addition of a tertiary amine increased shelf life and attainable solids. Similar improvement was found when ortho chloro groups were used for steric deactivation of two amine groups. Complete elimination of the gel problem was achieved by blocking two amine groups with acetyl or carbethoxy groups. Low molecular weight salt intermediates made from diester diacids and tetramines were also relatively free from gelation problems. A two-solution system for preparing pyrrone-imide copolymers provided another way to avoid gelation. Infrared and TGA studies showed that thermal curing gave good conversion to pyrrone only from dianhydride-tetramine polymers. Both blocked amine and salt types gave other structures some of which were probably crosslinked. jg p6
- Polymer Chemistry
- Organic Chemistry