Degradation of Chemical Threats by Brominated Polymer Networks

Abstract

Poly­(N-bromomaleimide) (PMAi-Br), poly­(N-vinylpyrrolidone)-bromine adducts (PVP–Br), and poly­(ethylene-alt-N-bromomaleimide) (PEMAi-Br) and their cross-linked networks are introduced as reactive, self-decontaminating components of protective barriers. Synthetic routes toward polymaleimides include free-radical copolymerization of maleimide with divinyl cross-linkers as well as amidation of poly­(ethylene-alt-maleic anhydride) with urea. The polymers are brominated by bromine in carbon tetrachloride or by copper­(II) bromide in dimethylformamide, with the active bromine contents up to and above 4 mequiv/g, or >30 wt %. The brominated polymer networks exhibit considerable swelling in water and possess reversible redox peak potentials in cyclic voltammetry experiments due to the redox reactions of the bromine present in the polymer structures. In acidic aqueous media, PVP–Br, PMAi-co-DVB-Br, and PEMAi-Br materials are able to degrade 100% of hydrazine, monomethylhydrazine, and 1,1-dimethylhydrazine down to concentrations below detectable levels of 0.15–0.25 mM. The hydrazine is converted to nitrogen gas. The insecticide malathion, tested as a simulant of a combat warfare agent VX, is efficiently and selectively oxidized to malaoxon in the presence of the brominated networks, whereas 2-(chloroethyl)­ethyl sulfide (CEES), a simulant of the sulfur mustard agent, is rapidly oxidized, in both vapor and liquid states, into its less-toxic sulfone derivative, 1-chloro-2-(ethylsulfinyl)­ethane (CEESO), with the only side product being 1,2-bis­(ethylthio)­ethane. The oxidation of CEES is proven to be selective, in that no toxic overoxidized CEES analogue, 1-chloro-2-(ethylsulfonyl)­ethane, is formed. The developed brominated polymer networks are versatile materials with potential applications in coatings, filters, fabrics, and sorbents.

Sensing and inactivation of Bacillus anthracis Sterne by polymer–bromine complexes

“…The complete coating of spores by polymer suggests that B. anthracis spores could be trapped within the polymer network, making it an ideal candidate for the sequestration of B. anthracis on a polymeric surface. Our ability to cross-link the polymer with other species to make the polymers insoluble in water broadens the application of these brominated polymers so they can be used not only in solution but possibly as coatings or thin films incorporated in fabrics (Bromberg et al 2014).…”

“…Bromination of polyallylamine modified with 4-aminopyridine (PAAm-APy) was accomplished as follows (Bromberg et al 2014). Dry polymer was suspended in a dark brown glass tube with chilled, freshly prepared 15 wt% bromine solution in carbon tetrachloride at 0°C under constant stirring in the dark.…”

“…Polyvinylpyrrolidone (PVP)-bromine complex was prepared by the bromination of commercially available linear PVP by a bromine solution in carbon tetrachloride (Bromberg et al 2014). Dry PVP (1 g) was suspended in an amber glass test tube with a freshly prepared 15 wt% bromine solution (chilled) in carbon tetrachloride (10 mL).…”

“…We believe that halogen-polymer complexes, either neutral or cationic, while being easier to prepare than CPs, can act as both sporicides and sensors. Polymer-bound halogens, and especially Nhalamines (compounds containing N-halogen bond), have been investigated as bactericides as well as oxidizing agents for various toxicants such as pesticides and hydrazines (Amitai et al 2010;Bromberg et al 2014). Herein, we addressed a question of whether it is possible to apply a simple complex between an active halogen and an available neutral or cationic polymer to inactivate B. anthracis spores in solution.…”

“…Since our concomitant studies demonstrated that PAAm modified with a nucleophilic cationic species, 4-aminopyridine, can efficiently degrade nerve agents (Bromberg et al 2014), we utilized that modified PAAm to complex with bromine as well, with a potential of gaining a polymeric species with a broad range of applicability in protective fabrics. We also examined if bromine compounds can be used for spore detection, simultaneous with spore inactivation, by monitoring release of DPA from B. anthracis after treatment with brominated polymers.…”