Optimisation of an nIR-Emitting Benzoporphyrin Pressure-Sensitive Paint Formulation

Area of Science:

• Aerospace Engineering
• Materials Science
• Optical Sensing

Background:

• Pressure-sensitive paints (PSPs) are optical sensors for measuring surface pressure on vehicle models in wind tunnels.
• Porphyrins, particularly red-emitting platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin, are standard luminophores in PSPs.
• Near-infrared (nIR)-emitting luminophores offer advantages over visible emitters, including wider spectral windows for dual-luminophore systems.

Purpose of the Study:

• To investigate the impact of varying luminophore loading on PSP performance.
• To evaluate the efficacy of nIR-emitting para-CF3 Pt(II) benzoporphyrin in PSP formulations.
• To identify optimal conditions for high-performance PSPs using benzoporphyrin luminophores.

Main Methods:

• Formulation of PSPs with varying concentrations of nIR-emitting benzoporphyrin luminophore in a polystyrene binder.
• Characterization of PSP performance metrics, including pressure sensitivity and temperature sensitivity.
• Optimization of luminophore loading percentage (wt/wt) relative to the binder.

Main Results:

• An optimal luminophore loading of 1.28% wt/wt benzoporphyrin to polystyrene binder was determined.
• The optimized PSP formulation exhibited low temperature sensitivity (0.61%/K at 100 kPa).
• The formulation achieved high pressure sensitivity (0.740%/kPa at 293 K).

Conclusions:

• Benzoporphyrin luminophores are effective for developing next-generation PSPs.
• Optimized benzoporphyrin-based PSPs demonstrate superior performance compared to current commercial options.
• This research highlights the potential of nIR-emitting luminophores for advanced aerodynamic testing applications.