Characterization of maleimide dimers in photo-cross-linked copolyimide films
| Autor: | Katharina Hunger, Laura Buschhaus, Claudia Staudt, Anna Pfeifer, Karl Kleinermanns, Nadine Schmeling |
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| Rok vydání: | 2012 |
| Předmět: |
chemistry.chemical_classification
Molecular Structure Chemistry General Physics and Astronomy Membranes Artificial Polymer Photochemical Processes Photochemistry Cyclobutane Maleimides Resins Synthetic chemistry.chemical_compound Cross-Linking Reagents Membrane Yield (chemistry) Polymer chemistry Quantum Theory Moiety Chemical stability Physical and Theoretical Chemistry Fourier transform infrared spectroscopy Dimerization Maleimide |
| Zdroj: | Physical Chemistry Chemical Physics. 14:4538 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/c2cp23355j |
| Popis: | Copolyimide membranes are established materials for the separation of gaseous and liquid mixtures. Cross-linking of the polymer strands improves the physical and chemical stability. The photo-cross-linking of a 6FDA-ODA/6FDA-DABA 4 : 1 copolyimide membrane containing maleimide side groups as linker was investigated by FTIR spectroscopy. IR absorption spectra of the copolyimide backbone, 3-hydroxypropyldimethyl maleimide and the copolyimide functionalized with 3-hydroxypropyldimethyl maleimide were measured before and after different irradiation times and compared to each other. For band assignment a normal mode analysis was performed. The backbone of the polymer and the maleimide linker can be well distinguished due to their different spectral band positions. Only the films containing a maleimide moiety perform a photoreaction, the polymer backbone does not interfere. Based on the difference spectra and the results of the DFT calculations it was shown that the trans- and the cis-cycloadduct as well as the previously suggested 2-2'-adduct without a cyclobutane ring are formed upon UV irradiation. Evidence for an oxetane-like photoproduct was not found. Different time constants for the increase of the product bands were observed. The cycloadduct accumulates with a shorter time constant (τ = 2 to 5 min) than the 2-2'-adduct (τ = 75 min). The yield of the photo-cross-linking reaction was determined by spectral deconvolution and kinetic fitting of several marker bands. For the copolyimide synthesized in this work, a maximum value of 6% was reached. The stiffness of the copolyimide backbone inhibits further photo-cross-linking. |
| Databáze: | OpenAIRE |
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