Sorption of Benzene, Toluene and Ethylbenzene by Plasticized Poly (Ethyl Methacrylate) Using Quartz Crystal Microbalance at 298.15K

Quartz crystal microbalances (QCM) are chemical sensors used for liquid and vapor sensing. In this thesis work, plasticized poly (ethyl methacrylate) (PEMA) coated QCM was used to study sorption behavior of benzene, ethylbenzene and toluene in respective polymer at 298.15K. Poly (ethyl methacrylate) (PEMA) is a promising polymer with solubility parameter close to BTEX compounds, but it\u27s glassy and rigid nature at room temperature make it less sensitive. The addition of plasticizers (Diisononyl cyclohexane-1,2-dicarboxylate (DINCH) and Diisooctyl azelate (DIOA)) lowers the glass transition temperature, provides flexibility and thus increases the free volume of the polymer to enhance analyte sorption. In order to study sorption processes of BTEX compounds from a vapor phase, QCM either with PEMA/DINCH or PEMA/DIOA film has been developed. The plasticizer concentration in PEMA was adjusted to obtain maximum sorption and sensitivity. Differential Scanning Calorimetry (DSC) was used to measure the glass transition temperature (Tg) of pure PEMA and plasticized PEMA. A drop-in glass transition temperature was noted with addition of plasticizer. Activity versus Weight fraction data for benzene, ethylbenzene and toluene in plasticized PEMA was collected using quartz crystal microbalance. It was observed that sorption of solvent vapors in PEMA increase with increasing concentration of plasticizers. The Flory-Huggins Model written for a ternary system was used to represent the experimental results