The role of anions in light-driven conductivity in diarylethene-containing polymeric ionic liquids†
Polymeric ionic liquids (PILs) with light-driven conductivity represent a new class of smart materials with potential applications as soft electronics, however the influence of counterion characteristics on their conducting properties remains unexplored. We synthesized a series of PILs based on copolymers of ethylene oxide and allyl glycidyl ether with different anions and light-responsive imidazolium-containing diarylethene (DAE) cations. This study shows that anion character impacts the photostationary state (PSS), magnitude of conductivity, and light-responsive properties of PILs. Compared with BF4−, anions featuring stronger cation–anion interaction (I−) and higher ratio of the ring-closed isomer at PSS (TFSI−) have a larger impact on the degree of change in ionic conductivity upon light irradiation. With this versatile synthetic platform, the electronic properties of the DAE cations can be non-invasively modulated by light with minimal structural change, providing the ability to study, in situ, cation–anion interaction without competing effects that arise from changes in polymer Tg or counterion size. These results are beneficial for understanding ion transport and structural design of smart light-responsive PILs.
- This article is part of the themed collection: Chemistry of polymers - Chemical Science symposium collection