Quartz Crystal Microbalance Studies of Dimethyl Methylphosphonate Sorption Into Trisilanolphenyl-Poss Films

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Date
2006-11-06
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Virginia Tech
Abstract

Developing methods to detect, adsorb, and decompose chemical warfare agents (CWAs) is of critical importance to protecting military and civilian populations alike. The sorption of dimethyl methylphosphonate (DMMP), a CWA simulant, into trisilanolphenyl-POSS (TPP) films has previously been characterized with reflection absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and uptake coefficient determinations [1]. In our study, the quartz crystal microbalance (QCM) is used to study the sorption phenomena of DMMP into highly ordered Langmuir-Blodgett (LB) films of TPP. In a saturated environment, DMMP sorbs into the TPP films, binding to TPP in a 1:1 molar ratio. Although previous work indicated these DMMP-saturated films were stable for several weeks, DMMP is found to slowly desorb from the TPP films at room temperature and pressure. Upon application of vacuum to the DMMP-saturated films, DMMP follows first-order desorption kinetics and readily desorbs from the film, returning the TPP film to its original state.

[1] Ferguson-McPherson, M.; Low, E.; Esker, A.; Morris, J. J. Phys. Chem. B. 2005, 109, 18914.

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Keywords
chemical warfare agent simulant, quartz crystal microbalance, trisilanolphenyl-POSS, Langmuir-Blodgett film
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