Interaction parameters for the uptake of sulfur mustard mimics into polyurethane films

Chemical warfare agent (CWA) sorption into polymeric coatings is an important consideration for preventing human exposure to CWAs. The specific nature of CWA–polymer interactions greatly influences the degree of gas uptake into a polymeric coating. By uncovering the role the various functional groups in CWAs play during gas sorption, better films and coatings can be engineered. This study utilized a quartz crystal microbalance to measure sulfur mustard (HD) analog (simulant) and hexane vapor uptake into polyurethane films. Analysis of the uptake data with Flory–Huggins theory yielded interaction parameter values (χ) between 0.24 and 0.40 for each HD simulant-polyurethane system compared to 0.97 for hexane, revealing the importance of the chlorine and sulfur groups in gas uptake at the thin film interface. We predict similar uptake behavior for HD in polyurethane coatings due to structural similarities between HD and the simulants.