The synthesis, characterization and third-order nonlinear optical character of poly(2,5-dipropargyloxybenzoate) containing a polar aromatic diacetylene

The glass transition temperature of the novel compound, poly( 2, 5-dipropargyloxybenzoate) containing a polar aromatic diacetylene was 105 °C and differential scanning calorimetry showed two exothermic peaks due to the opening of the hexa-2,4-diynylene-1,6-dioxy group and the aromatic diacetylene group. Two types of free radical were detected in the electron spin resonance spectra of the heated polymer, one formed by cross-linking of the main chain hexa-2,4-diynylene-1,6-dioxy group and another arising from the aromatic chromophore diacetylene. The third-order nonlinear optical susceptibility, χ (3), of the polymer film determined using the Z-scan technique was −4.5 ± 1 × 10 −10 esu. When the films were irradiated by UV light at 140 °C, they formed micro-cracks due to intense cross-linking.