Photoactive polyurethanes based on 2,2′-dihydroxyazobenzene fluorescent segments
| Autor: | Marcelo Meira Faleiros, Maria I. Felisberti, Teresa D. Z. Atvars, Luís Gustavo Teixeira Alves Duarte, Germana Maria Santos Paiva |
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| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Materials science Absorption spectroscopy Photoisomerization 02 engineering and technology Polymer 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials chemistry.chemical_compound Crystallography Monomer chemistry Materials Chemistry Molecule Physical and Theoretical Chemistry 0210 nano-technology Caprolactone Conformational isomerism Spectroscopy Polyurethane |
| Zdroj: | Journal of Molecular Liquids. 337:116481 |
| ISSN: | 0167-7322 |
| Popis: | This article presents the synthesis and structural, thermal and dynamic mechanical characterization of segmented polyurethane - PCLDHAB - based on poly(caprolactone)-diol (PCL-diol) as a flexible segment, and polyurethane-diol (PU-diol) as a rigid segment based on 2,2′-dihydroxyazobenzene (2,2′-DHAB). While the precursors PU-diol and PCL-diol are rigid and waxy materials, respectively, PCLDHAB is a flexible, semi-crystalline polymer, which has a heterogeneous amorphous phase. To better understand the absorption spectra of the polyurethanes, theoretical predictions by DFT and TD-DFT of a model molecule in DMF (implicitly added) were carried out. The model molecule was a fragment of the hard segment of the polyurethane’s chain, containing one 2,2′-DHAB and two 4′-isocyanate-4′-methylbenzene fragments, bonded to each other by carbamate bonds, the 4-isocyanate-4′-metylbenzene-alt-2,2′-dihydroxyazobenzene. Similar to 2,2′-DHAB, PU-diol and PCLDHAB do not show photoisomerization, however they emit fluorescence. 2,2′-DHAB segments in the polyurethane chains present different conformations with distinct spectroscopic characteristics. However, the conformer’s proportion in the polymer chains differs from the 2,2′-DHAB monomers in DMF solution. 2,2′-DHAB emits in two ranges in the UV–vis spectrum while its polyurethanes emit in three ranges, covering a broader wavelength range from ultraviolet to visible. |
| Databáze: | OpenAIRE |
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