Qiu F.,Jiangsu University |
Qiu F.,Jiangsu Provincial Key Laboratory of Modern Agricultural Equipment and Technology |
Zhang W.,Jiangsu University |
Yang D.,Jiangsu University |
And 3 more authors.
Journal of Applied Polymer Science | Year: 2010
An optically active levoazobenzene polyurethane (PU) was synthesized and was based on the chromophore 4-(4′-nitrophenylazo) phenylamine, the chiral reagent L(-)-tartaric acid, and toluene diisocyanate. The chemical structure and thermal properties were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, 1H-NMR spectroscopy, and differential scanning calorimetry. The PU had high number-and weight-average molecular weights up to 52 300, a large glasstransition temperature of 235.7°C, and an optical rotation of -18.06°, The optical parameters, including the refractive index (n) and thermo-optic coefficient (dn/dT); the dielectric constant (ε) and its variation with temperature; and the thermal volume expansion coefficient and its variation with temperature of PU were obtained. The dn/dT and ε values for the polymer were in the range -4.1200 to 3.6257 × 10-4 °C-1 and 2.00 ± 0.11, respectively. The dn/dT values were one order of magnitude larger than those of inorganic glasses, such as zinc silicate glass (5.5 × 10-6 °C-1) and borosilicate glass (4.1 × 10-6 °C-1), and were larger than organic materials, such as polystyrene (-1.23 × 10-4 °C-1) and poly(methyl methacrylate) (-1.20 × 10-4 °C-1). The ε values were lower than that of alicyclic polyimide and semiaromatic polyimide. The obtained PU is expected to be useful for optical switching and optical waveguide areas. The conclusion has a little significance for the development of a new digital optical switch. © 2009 Wiley Periodicals, Inc. Source