Dissolution of polymer films in supercritical carbon dioxide using a quartz crystal microbalance

The dissolution kinetics of polymeric materials in CO2 is crucial to the understanding, design and control of CO2-based environmentally benign lithography processes. This study utilizes the quartz crystal microbalance (QCM) to monitor and evaluate the dissolution of poly(1,1-dihydroperfluorooctyl methacrylate-r-2-tetrahydropyranyl methacrylate), poly(FOMA-r-THPMA), polymer films in supercritical CO2 over a range of temperatures and pressures. Polymer dissolution rates at the range of pressures studied were evaluated to quantify the dissolution kinetics for the polymer. The experiments revealed that the polymer dissolution in supercritical CO2 undergoes two apparent processes: a rapid absorption of CO2 into the polymer film followed by a gradual dissolution of polymer film into the CO2 at the polymer–CO2 interface. The nature of these interfacial phenomena and their associated effect on the rate are discussed.