| Under photo and thermal treatment, the configuration of azobenzene compoundscan be trans-cis isomerized. Material containing azobenzene structure has greatpotential for application as a new class of rewritable medium with high-densityrecording performance.In this work a serials azobenzene compounds with reactive functional groups weresynthesized by diazo-coupling and Williamson reaction: 4-hydroxy-4'-nitroazobenzene (â… ) and 4-hydroxy-4-nitro azobenzene (â…¢) were synthesized with4-nitroaniline and 4-cyanoaniline. 4'-Nitro azobenzene glycidol ether (â…¡) and4-cyano azobenzene glycidol ether (â…£) were synthesized with (â… ), (â…¢) andepichlorohydrin (ECH). These compounds were characterized by Melting Point,FT-IR, 1H-MNR and element analyzing. Two types of hyperbranched polyesterswith terminal -COOH groups were prepared from the alter ring openingpolymerization of anhydride and epoxy compounds: HBP-1 from succinic anhydrideand glycidoi, HBP-2 from trimellitic anhydride (TMA) and ECH. The structures ofHBPs were characterized by FT-IR, 1HNMR and 13C-NMR and GPC. The moleculeweight, relative to PS, and the index of molecule weight distribution for HBP-1 andHBP-2 were 2213g/mol, 1.69 and 1413g/mol, 1.77, respectively, as determined byGPC. Hyperbranched polyesters functionalized with 4'-nitro azobenzenes, f-HBP-1and f-HBP-2, were prepared, respectively, by the reaction of the carboxyl groups on HBP-1 and on HBP-2 with epoxy groups of (â…¡). The functionalized polymers werecharacterized by FT-IR, UV/Vis, 1H-NMR, DSC and GPC.The photo-induced trans/cis photo-isomerizations were investigated forâ…¡,f-HBP-1 and f-HBP-2. They all showed the photochromic properties uponirradiation with UV light. Because the azobenzene groups in HBP was restricted bythe macromolecule, the photoisomerization became slower, as compared with thesmall molecule counterpart. In solution, however, the effects of macromolecules onthe azobenzen groups were not obvious for the more soft polyesters f-HBP-2. |
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