Microwave Promoted Addition of Organosiloxanes to Hydroxyl Containing Substrates for Facile Synthesis of Chemical and Biological Warfare Agent Reactive Polymers

Abstract

The primary focus of this work was the synthesis and characterization of materials efficacious in detoxifying/killing chemical and/or biological threat agent surrogates, including Bacillus anthracis spores, in militarily relevant environments. To this end, it was shown: that polymers containing =5 ppt active chlorine in the form of polymer linked hydantoin chloramides demonstrated significant activity against biological and chemical threat agent surrogates; that =5 ppt active chlorine is easily attained on polymeric substrates containing hydroxyl groups using a minimum amount of solvent and reduced amounts of reagents by the microwave grafting of 3-(3-triethoxysilylpropyl)-5,5-dimethylhydantoin (BA-1) onto the substrate, followed by exposure to an appropriate chlorinating agent; through environmental stability experiments that attenuation of active chlorine from the chlorinated hydantoin-bound polymers over time, with the degree of loss dependent on the conditions; and finally, that, in all cases in this work, rechlorination of the spent polymer bound-hydantoin moieties was achieved. Recognizing the advantages of using microwave irradiation as an alternate means to conventional heating for the attachment of siloxanes to hydroxyl containing substrates and the recognition of the differences between the heat-treated analogs remains the most significant discoveries reported in this work. Compared to the most effective heat treatment for addition of BA-1 to boehmite, controlled application of microwave energy enhanced the capacity for incorporation of active chlorine more than fourfoldfrom a lower relative concentration of BA-1. To demonstrate the generality of this method of enhancing silicone coupling, microwave irradiation was used to synthesize discrete hypervalent silicon compounds faster, using less solvent, and in higher purity and yield compared to traditional synthetic processes. Finally, the tactical purpose of this program was realized: the microwave-enhanced BA-1-treated substrates caused 5-log reductions in viable counts of B. anthracis Sterne spores.