Polymers and supercritical fluids: Opportunities for vibrational spectroscopy

Supercritical fluids are used for enhanced processing of polymeric materials. Therefore, there is a need to understand how supercritical fluids interact with polymeric materials and how they may modify many facets of process operations. In situ spectroscopy provides a route for understanding and optimising polymer processing with supercritical fluids. In situ spectroscopy probes interactions between supercritical CO2 and polymers at a molecular level and provides a fundamental understanding of the origin of the plasticising effect of supercritical carbon dioxide on glassy polymers. The changes in polymers subjected to supercritical fluids have been elucidated via in situ ATR(Attenuated Total Reflectance)-IR spectroscopy. The key feature of our new approach is the use of a modified diamond ATR accessory to measure spectra of polymers subjected to high-pressure gas, supercritical fluids or near-critical water. A variety of novel applications for the use of in situ ATR-IR spectroscopy to polymers are described.