To monitor the viscosity in situ of polymers in real-time remains a challenge as traditional rheological methods can’t be utilized in confined environments. In this study, [Cu(I)(diptmp)2]+ (diptmp = 2,9-diisopropyl-2,4,7,8-tetramethyl-1,10-phenanthroline) was incorporated into industrial adhesives as an optical probe. The luminescence of the [Cu(I)(diptmp)2]+ was monitored during the curing process (viscosity increases) for real time sensing of viscosity via changes in luminescence. [Cu(I)(diptmp)2] in epoxy glue showed increased emission lifetime of the triplet metal to ligand charge transfer (3MLCT) state in real-time as the glue was cured. Monitoring the real time viscosity by swelling (viscosity and lifetime decrease) and by unswelling (viscosity and lifetime increase) of the polymer film was also performed to verify the reversibility and absence of initiator chemical quenching. Viscosity in opaque samples was also measured which showed a similar correlation of increased luminescence lifetime as the viscosity increase during curing of the adhesive. [Ru(II)(bpy)3]2+ (bpy = bipyridine) as a control was used to monitor lifetime changes showing that the [Cu(I)(diptmp)2]+ optical probe had higher emission lifetimes and was more ubiquitous as a real-time viscosity sensor in a variety of systems. These results highlight how the [Cu(I)(diptmp)2]+ optical probe can be used to sense small viscosity changes, including those that are unable to be detected using traditional polymer characterization methods such as rheology.

Real-time viscosity monitoring using luminescent Cu(I) phenanthroline complex: Applications in inorganic sensors

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.