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Synthesis and Properties of Multi-Block Copolymers Based on Poly(oxyethylene)s and Aromatic Polyamides

Polyether–aramid multi-block copolymers having high structural regularity were synthesized by the direct polycondensation of poly(oxyethylene)dicarboxylic acids with amine-terminated telechelic aromatic polyamide (aramid) oligomers using triphenyl phosphite and pyridine as the condensing agent. The polymerizations at a total oligomer concentration of 100—200 gl−1 in a mixture of pyridine and N-methyl-2-pyrrolidone afforded the block copolymers having inherent viscosities of 0.4—0.9 dlg−1. These multi-block copolymers are soluble in N,N-dimethylacetamide (DMAc) and gave transparent, ductile, and elastomeric films by casting from DMAc solutions. Moisture regain of these films is 5—6% in 60% relative humidity at 25°C. On the DTA curves in nitrogen, these copolymers exhibited two strong exothermic peaks at around 270 and 410°C; the former temperature corresponds well to the initial weight loss temperature on the TG curves. In the polyether–aramid multi-block copolymers, tensile strength and modulus of the films fall with an increase in the poly(oxyethylene) content, whereas elongation at break increases.