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.

No abstract

No abstract

No abstract

vacuum oven at 100-110 °C overnight.Method B. The same O-alkylation procedure may be employed with a 25% solution of tetrabutylammonium hydroxide. Two modifications are required in the previous experiment if this base is used. First, the reaction time is less than 1 day, and second, during the workup sodium nitrate (3-fold excess) is added just after neutralization to produce an anion-exchange reaction with the tetrabutylammonium salt. Since the quaternary ammonium nitrate is more water soluble than the corresponding halide derivative, the sodium nitrate addition lessens the time required to wash out the tetrabutylammonium byproduct. The sodium salts were readily removed by the hot water extractions. The Soxhlet extraction time is about the same with this modified procedure as before.