Diels-Alder Polymer Networks with Temperature-Reversible Cross-Linking-Induced Emission

A novel synthetic strategy gives reversible cross-linked polymeric materials with tunable fluorescence properties. Dimaleimide-substituted tetraphenylethene (TPE-2MI), which is non-emissive owing to the photo-induced electron transfer (PET) between maleimide (MI) and tetraphenylethene (TPE) groups, was used to cross-link random copolymers of methyl (MM), decyl (DM) or lauryl (LM) methacrylate with furfuryl methacrylate (FM). The mixture of copolymer and TPE-2MI in DMF showed reversible fluorescence with on/off behavior depending on the Diels-Alder (DA)/retro-DA process, which is easily adjusted by temperature. At high temperatures, the retro-DA reaction is dominant, and the fluorescence is quenched by the photo-induced electron transfer (PET) mechanism. In contrast, at low temperatures, the emission recovers as the DA reaction takes over. A transparent PMFM/TPE-2MI polymer film was prepared which shows an accurate response to the external temperature and exhibited tunable fluorescent turn on/off behavior. These results suggest the possible application in areas including information security and transmission. An example of invisible/visible writing is given.

Automated summary

A novel synthetic strategy was used to create reversible cross-linked polymeric materials with tunable fluorescence properties. By adjusting the temperature, the fluorescence behavior of the materials can be controlled, showing potential applications in areas such as information security and transmission.