Ionomeric polyurethanes of pyridinium type with side azobenzene groups

• Published in: Journal of applied polymer science 2002-10, Vol.86 (5), p.1240-1247
• Main Authors: Buruiana, Tinca, Buruiana, Emil C.
• Format: Article
• Language: English
• Subjects: Applied sciences; azo polymers; elastomers; Exact sciences and technology; functionalization of polymers; Organic polymers; photo; Physicochemistry of polymers; Polymers with particular properties; polyurethane ionomers; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.11071

New polyurethane cationomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with nitroazobenzene groups were studied. As a starting polymer, a polyurethane based on poly(tetramethylene oxide)diol, isophorone diisocyanate, and 2,6‐bis(hydroximethyl)pyridine was used. After a preliminary metalation of the above polymer with natrium hydride, by reaction of polyurethane N‐sodate with 4‐nitro‐4′(β–iodoethylurethane)azobenzene, chromophoric groups between 2.85 and 10.53 wt % could be incorporated instead of hydrogen. Such polymers partially functionalized with azobenzene and further quaternized with methyl iodide led to the formation of pyridinium polyurethane cationomers N‐modified with nitroazo groups. The photosensible properties of the azobenzene chromophore in a polymer solution and film state indicated important differences in their photoresponse. In the polymer solution, the trans–cis photoisomerization of the chromophore is accompanied by an irreversible photobleaching effect, while under the same UV irradiation conditions, the ionomeric films exhibited an enhanced photostability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1240–1247, 2002