Synthesis and characterization of photoactive polyurethane elastomers with 2,3-dihydroxypyridine in the main chain |
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Authors: | Stefan Oprea Violeta Otilia Potolinca |
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Affiliation: | (1) “Petru Poni” Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, No. 41-A, 700487 Iasi, Romania |
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Abstract: | Photoactive polyurethane elastomers with pyridine derivatives in the polymer backbone were synthesized by chain-extending
isocyanate end-capped prepolymers with 2,3-dihydroxypyridine. The isocyanate-terminated prepolymers were obtained from poly(tetramethylene
oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6-hexamethylene diisocyanate. The properties of the linear heterocyclic
polyurethane were compared with properties of the crosslinked heterocyclic polyurethane obtained by chain extension with various
crosslinkers. Heterocyclic polyurethane elastomers were characterized using Fourier transform infrared spectroscopy (FTIR),
thermo-gravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurements, and mechanical analysis.
Static mechanical measurements showed greater elongation and tensile strength for polyurethanes with a lower content of heterocyclic
groups in the hard segment. The static contact angles of the cast films of these polymers indicated that the nature of the
hard segment influences the surface polarity. The dynamic mechanical spectra revealed that linear polymers have two transition
temperatures as results from a clear phase separation caused by high-intermolecular hydrogen bonds in the regions of pyridine
units and urethane groups. Polyurethane elastomer films with pyridine moieties in the main chain form a photosensitive material.
If stored in laboratory conditions (light, ambient air atmosphere), the color of the films changes from white to black. These
photo-induced structural changes are studied by H NMR measurements. |
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