Cis–trans isomerization and optical laser writing in new heterocycle based azo-polyurethanes

Three new azo-polyurethanes containing the s-triazolo[3,4-b]thiadiazole heterocycle have been prepared and characterized. The polymers showed glass transition temperatures between 183 °C and 232 °C and a moderate to good thermal stability in air. The thermal cis–trans isomerization around the azo group was analyzed in solution and the kinetic constant of this process was calculated.One of the synthesized polymers was processed in form of thin films (thickness was 1.2 μm) and some experiments of optical laser writing were performed on it: three different surface relief gratings (SRGs) structures were realized at micrometer scale (a square, a concentric square pattern and a grating) indicating this polymer as an interesting candidate for the azo-lithography.

► Synthesis and characterization of new azo-polyurethanes containing the s-triazolo[3,4-b]thiadiazole heterocycle. ► First order regime for cis–trans isomerization in solution. ► Surface relief gratings on high Tg polymers thin films. ► Features height depending on polarization/writing direction.