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Photo-Isomerization of the Olefinic Group

المؤلف:  A. Ravve

المصدر:  Principles of Polymer Chemistry

الجزء والصفحة:  756

2026-03-09

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Photo-Isomerization of the Olefinic Group

An example of olefinic groups rearrangement is work by Onciu et al. [201] who formed three bis (trimellitimide)s by condensing three aromatic diamines with trimellitic anhydride. This was followed by preparation of two series of photo-reactive copoly(amide-imide) s by direct polycondensation of the bis(trimellitimide)s and 1,4-phenylenediacrilic acid with either 4,4-diphenyl methanediisocyanate in one case or with 1,6-diisocyanatohexane in another case, respectfully. All of the copoly(amide-imide) s were found to be soluble in polar aprotic solvents and to yield transparent, flexible, and tough films [201]. When the polymers are irradiated in solution, the p-phenylene diacryloyl units undergo trans–cis photo-isomerization and (2 + 2) photo-cycloadditions [201]. The fully aromatic polyamides also undergo a photo-Fries rearrangement. The photo-Fries reaction, however, is completely suppressed in polymers that contain an aliphatic amide moiety [22]. The same processes are also observed in the polymer films [201]. Polymers prepared by condensation of 4,40-diacetylstiblene as the bis(ketomethylene)monomer with 4,40-diamino-3,30-dibenzoylstilbene, a bi (amino ketone), exhibit photo-viscosity effects in dilute solutions due to cis-trans isomerization [202]. The preparation of the polymers and the photo rearrangements can be illustrated as follows:

The changes in viscosity can vary from 2 to 23% as a result of irradiation.