Azobenzenes in polymer networks
The photoswitching dynamics of azobenzene (AB) and many azobenzene derivatives have been rather extensively studied in solution by ultrafast time-resolved methods for some time. For many applications, however, the ABs have to be embedded in complex environments such as liquid crystals, polymers, thin films or composite materials, where the photoswitching has not been investigated in much detail to date although the light-induced transformations may be strongly affected by the surrounding matrix.
Disperse Red 1 (DR1, left) attached to a side chain and 4,4'-bis(acetamido)-azobenzene (BAAB, right) in the main chain of PBMA.
In order to elucidate the important mechanisms under the much more complex conditions in polymer micronetworks than in solution, we are investigating the trans-to-cis photoisomerization dynamics of AB derivatives in cross-linked colloidal polymethylmethacrylate (PMMA) and polybutylmethacrylate (PBMA) micronetworks by femtosecond time-resolved fluorescence up-conversion spectroscopy. Our results show huge differences in the dynamics of azobenzenes linked to polymers compared to free azobenzenes in solution.
- J. Bahrenburg, F. Renth, F. Plamper, W. Richtering, F. Temps, "Femtosecond Spectroscopy Reveals Huge Differences in the Photoisomerization Dynamics of Azobenzenes Linked to Polymers and Azobenzenes in Solution," Phys. Chem. Chem. Phys.16, 11549 - 11554 (2014). DOI: 10.1039/C4CP01196A