title: Sorption of dimethyl methylphosphonate within Langmuir-Blodgett films of trisilanolphenyl polyhedral oligomeric silsesquioxane.
abstract: Trisilanolphenyl polyhedral oligomeric silsesquioxane (POSS) molecules are used to create well-ordered Langmuir-Blodgett films containing silanol groups that interact strongly with dimethyl methylphosphonate (DMMP), a commonly used simulant for the chemical warfare agent sarin. The interaction of DMMP within multilayer POSS films is studied by uptake coefficient and temperature-programmed desorption (TPD) measurements, as well as reflection-absorption infrared spectroscopy (RAIRS). Results indicate a low uptake probability; however, in a DMMP-saturated atmosphere, the organophosphonate molecules are capable of diffusing into and adsorbing within the films. TPD and RAIRS measurements reveal no evidence of DMMP decomposition within the film. Rather, DMMP is found to desorb molecularly with a desorption energy of 122 kJ/mol. RAIRS reveals that strong hydrogen-bonding interactions between the phosphoryl groups of the organophosphonate molecules and the silanol groups of the POSS molecules are responsible for the high sorption energy of the system.
authors.affiliation: Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
authors.forename: Melinda K
authors.initials: MK
authors.lastname: Ferguson-McPherson
authors.forename: Emily R
authors.initials: ER
authors.lastname: Low
authors.forename: Alan R
authors.initials: AR
authors.lastname: Esker
authors.forename: John R
authors.initials: JR
authors.lastname: Morris
mesh_terms: D000327:Adsorption; D008567:Membranes, Artificial; D009943:Organophosphorus Compounds / Q000737:chemistry*; D017646:Organosilicon Compounds / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D008567:Membranes, Artificial; D009943:Organophosphorus Compounds; D017646:Organosilicon Compounds; C031116:dimethyl methylphosphonate