N-Alkylation and Hofmann elimination from thermal decomposition of

Macromolecules 1991,24, 1731-1735

1731

N-Alkylation and Hofmann Elimination from Thermal Decomposition of R4N+ Salts of Aromatic Polyamide Polyanions: Synthesis and Stereochemistry of N-Alkylated Aromatic Polyamides Robert R. Burch' and Lewis E. Manring Central Research and Development Department,' E. I. du Pont de Nemours and Company, Inc., Experimental Station, Wilmington, Delaware 19898 Received June 25, 1990; Revised Manuscript Received September 18, 1990 ABSTRACT The reaction of aromatic polyamides such as poly@-phenyleneterephthalamide)(PPTA)with (n-Bu)rN+-OHor EtrN+-OHgives dimethyl sulfoxide (DMSO)soluble polyanions as the (n-Bu)rN+or Et4N+ salts derived from deprotonation of the amide hydrogen. The n(R4N+)PPTAnsalts thermally decompose by Hofmann elimination to yield neutral PPTA, olefin, and NRs. Dissolving PPTA by deprotonation and thermally decomposing the R4N+ salt can be used to process the polymer. Films cast from DMSO solutions of nR4N+PPTAn-convert from polyanion to a PPTA film when heated to about 200 OC, removing solvent and volatile byproducts,and leaving a crisp PPTA film. Model studies show that N-alkylationcompetes with the Hofmann elimination of nRIN+PPTA"-. Whereas ~(~-BU)~N+PPTA"undergoes extensive N-butylation, nEt4N+PPTAn-shows only trace amounts (