Calorimetric measurements of heat of sorption in polymer films: A molecular modeling and experimental study

We report a combined molecular modeling and experimental effort to predict and measure the heat of sorption of target molecules in a polymer film. The primary focus of this work is to demonstrate and validate the applicability of molecular modeling techniques as a predictive tool to evaluate polymeric sensing films for micro-calorimetric chemical sensor applications. In the current investigation, molecular modeling studies were performed prior to experimental measurements to predict the heat of sorption (ΔHsorpt) of a target analyte in a polymer film. Experimental measurements for the heat of sorption were performed using a quartz crystal microbalance/heat conducting calorimeter setup. The system under investigation was isopropanol in ethyl cellulose polymer film. The average ΔHsorpt predicted by molecular modeling at 22 °C was found to be 39.7 kJ/mol (standard deviation = 2.6 kJ/mol), which compares well with the average measured experimental value of 30.2 kJ/mol (standard deviation = 7.2 kJ/mol).