The photo curing extent of styrenic block copolymer (SBC)-based adhesive formulations applied as a uniform layer on a Mylar film can be readily determined by Fourier transform infrared spectroscopy (FTIR). Recently, a pulsed KrF excimer laser (emission line at 248 nm, pulse width ~30 ns) was incorporated as the UV source. The adhesive formulation prepared without the addition of a photoinitiator was exposed to the UV laser beam for various durations up to 3 µs (100 laser pulses) in order to cure the adhesive.
The absorption band at 910 cm-1 (vinyl groups) was followed to evaluate the photo-curing process. The determination of percent cure is an important parameter to optimize both the formulation manufacturing process and the adhesive performance.