The synthesis and properties of a class of high molecular weight, filmand fiber-forming, rodlike, aromatic polyamides containing all-para-linked substituted-biphenylene and/or -stilbene repeat units are described. Substituents are placed on the aromatic rings (or double bond of the stilbene moiety) so as to force them into a noncoplanar conformation. The effect of this noncoplanarity is to reduce the crystallinity (to <10%) of even highly oriented films, enhance solubility, and reduce or completely eliminate absorption of visible radiation. Another consequence of this noncoplanar conformation is to confer a substantially cylindrical electron density distribution about the long axis of the polymer backbone which in many examples enhances the repeat unit anisotropy and may contribute to the unusually high birefringence.

The solubility of a series of para‐linked, substituted phenyl, biphenyl, terphenyl, and quaterphenyl polyamides is reported. Most of these polymers are soluble in amide solvents without lithium chloride, and several are soluble in ethers and/or ketones. The results indicate that solubility in this class of polymers is affected by the position, polarizability and size of the substituents, enantiomeric purity, and the number of non‐coplanar biphenyl rings per repeat unit.

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