Reversible Modulation of Conductivity in Azobenzene Polyelectrolytes Using Light

• Published in: ACS applied polymer materials Vol. 5; no. 7; pp. 4698 - 4703
• Main Authors: Nguyen, Phong H., Scheuermann, Angelique M., Nikolaev, Andrei, Chabinyc, Michael L., Bates, Christopher M., Read de Alaniz, Javier
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14-07-2023
• Subjects: ionic liquid; photoswitchable isomerization; polyelectrolyte; azobenzene coordination; light-responsive
• ISSN: 2637-6105; 2637-6105
• DOI: 10.1021/acsapm.3c00265

Incorporating light-responsive azobenzene into polyelectrolytes couples photoinduced changes in steric interactions and polarity to ionic conductivity. The reversible isomerization of an azobenzene moiety yields a 2–7 times change in the ion conductivity (σtrans > σcis) depending on the polymer composition. These trends cannot be explained by differences in the glass-transition temperatures of the polymers. Instead, UV–vis spectroscopy reveals a bathochromic shift in the π → π* transition of cis-poly­(azobenzene) upon adding lithium bis­(trifluoromethane)­sulfonimide (LiTFSI) salt, suggesting that coordination of the cis isomer with Li+ is responsible for its lower conductivity. In summary, azobenzene is a simple and convenient functional unit to control the conductivity of polymeric materials using light.