Self-Decontaminating Fibrous Materials Reactive toward Chemical Threats

Polymers that possess highly nucleophilic pyrrolidinopyridine (Pyr) and primary amino (vinylamine, VAm) groups were prepared by free-radical copolymerization of <i>N</i>,<i>N</i>-diallylpyridin-4-amine (DAAP) and <i>N</i>-vinylformamide (NVF) followed by acidic hydrolysis of NVF into VAm. The resulting poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) copolymers were water-soluble and reacted with water-dispersible polyurethane possessing a high content of unreacted isocyanate groups. Spray-coating of the nylon–cotton (NYCO), rayon, and poly­(<i>p</i>-phenylene terephthalamide) (Kevlar 119) fibers pretreated with phosphoric acid resulted in covalent bonding of the polyurethane with the hydroxyl groups on the fiber surface. A second spray-coating of aqueous solutions of poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) on the polyurethane-coated fiber enabled formation of urea linkages between unreacted isocyanate groups of the polyurethane layer and the amino groups of poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF). Fibers with poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) attached were compared with fibers modified by adsorption of water-insoluble poly­(butadiene-<i>co</i>-pyrrolidinopyridine) (polyBPP) in terms of the stability against polymer leaching in aqueous washing applications. While the fibers modified by attachment of poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) exhibited negligible polymer leaching, over 65% of adsorbed polyBPP detached and leached from the fibers within 7 days. Rayon fibers modified by poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) were tested for sorption of dimethyl methylphosphonate (DMMP) in the presence of moisture using dynamic vapor sorption technique. Capability of the fibers modified with poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) to facilitate hydrolysis of the sorbed DMMP in the presence of moisture was uncovered. The self-decontaminating property of the modified fibers against chemical threats was tested using a CWA simulant diisopropylfluorophosphate (DFP) in aqueous media at pH 8.7. Fibers modified with poly­(DAAP-<i>co</i>-VAm-<i>co</i>-NVF) facilitated hydrolysis of DFP with the half-lives up to an order of magnitude shorter than that of the unmodified fibers. The presented polymers and method of multilayer coating can lead to a development of self-decontaminating textiles and other materials

Postsynthetic Functionalization of Mg-MOF-74 with Tetraethylenepentamine: Structural Characterization and Enhanced CO₂ Adsorption

Postsynthetic functionalization of magnesium 2,5-dihydroxyterephthalate (Mg-MOF-74) with tetraethylenepentamine (TEPA) resulted in improved CO₂ adsorption performance under dry and humid conditions. XPS, elemental analysis, and neutron powder diffraction studies indicated that TEPA was incorporated throughout the MOF particle, although it coordinated preferentially with the unsaturated metal sites located in the immediate proximity to the surface. Neutron and X-ray powder diffraction analyses showed that the MOF structure was preserved after amine incorporation, with slight changes in the lattice parameters. The adsorption capacity of the functionalized amino-Mg-MOF-74 (TEPA-MOF) for CO₂ was as high as 26.9 wt % versus 23.4 wt % for the original MOF due to the extra binding sites provided by the multiunit amines. The degree of functionalization with the amines was found to be important in enhancing CO₂ adsorption, as the optimal surface coverage improved performance and stability under both pure CO₂ and CO₂/H₂O coadsorption, and with partially saturated surface coverage, optimal CO₂ capacity could be achieved under both wet and dry conditions by a synergistic binding of CO₂ to the amines as well as metal centers