In situ and time-resolved infrared detection of the reactivity induced by electrons in polymer films

The real time and in situ analysis of chemical reactions such as polymerization reactions, polymer degradation, and oxidation of polymers is of utmost importance. Surprisingly, only few experimental tools allowing this are available. To bridge this gap, we have developed a new experimental setup coupling a 60 keV electron gun with an infrared spectrometer operating in the mid-IR region (800-4000 cm^-1) and associated with the rapid scan mode. The measurements are performed using the infrared reflection absorption spectroscopy approach. We worked here with 0.5-25 ms pulses for which the dose per pulse ranges from 4 to 200 kGy. Combining pulse electrons with rapid scan analysis enables performing experiments with a time resolution of 80 ms (and above). Therefore, this new platform can, for instance, give direct insights into reaction mechanisms at stake during the degradation of polymers. First results on a bisphenol A polycarbonate irradiated under vacuum enabling the validation of this new setup and also the recording of time-resolved spectra are presented. Reaction mechanisms are then proposed.