Synthesis and Properties of New N‐Methylated Aliphatic‐Aromatic Polyamides Derived from N,N′‐Dimethylalkylenediamines and 4,4′‐Biphenyl‐dicarboxylic and 4,4″‐p‐Terphenyldicarboxylic Acids

Two new series of N‐methylated aliphatic‐aromatic polyamides were prepared by interfacial polycondensation of N,N ′‐dimethylalkylenediamines having 6–10 methylene units with 4,4′‐biphenyldicarbonyl and 4,4″‐p‐terphenyldicarbonyl chlorides. All of the N‐methylated polyamides were soluble in chlorinated hydrocarbon solvents, and the solubilities of the biphenyl‐based polyamides were higher than those of the terphenyl‐containing polymers. The biphenyl‐bearing polyamides with an even‐number of methylene units were crystalline and their odd‐numbered neighbors were amorphous, whereas all of the terphenyl‐containing polymers were crystalline. The melting temperatures of the terphenyl‐based polyamides (220–307°C) were higher than those of the biphenyl‐bearing polymers (180–207°C). Among these N‐methylated polyamides, the terphenyl‐containing polyamide having 7 methylene units showed enantiotropic liquid crystallinity.