Amorphous rigid-rod polymers

• Published in: Progress in polymer science 1989, Vol.14 (1), p.47-89
• Main Authors: Gaudiana, R.A., Minns, R.A., Sinta, R., Weeks, N., Rogers, H.G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization
• ISSN: 0079-6700; 1873-1619
• DOI: 10.1016/0079-6700(89)90017-8

The properties are reveiwed of three classes of rodlike polymers containing the noncoplanar 2,2'-disubstituted biphenyl moiety, namely, polyamides, polyesters, and, in a very abbreviated form, polyesteramides. It is indicated that these very high molecular weight materials exhibit, in combination, several very unique properties. They are colorless due to the non-conjugated repeat units and yet they are simultaneously highly refractive and birefringent. They are completely or nearly completely amorphous. They have low glass transition temperatures. The esters exhibit extremely low solid--nematic transition temperatures. None of these polymers form lyotropic solutions in any solvent, but they are soluble in common solvents, such as ethers, ketones, and low boiling chlorinated solvents (in some examples to as much as 40-50%). The noncoplannar, 2,2'-disubstituted biphenyl moiety is thought to be the key factor leading to this unique combination of properties. Of the biphenyls synthesized to date, the trifluoromethyl substituent is by far the most effective at enhancing nearly all of these properties. 98 ref.--AA