Synthesis and characterization of a hyperbranched hydrogen bond acidic carbosilane sorbent polymer

Abstract

Sorbent polymers can be designed to target molecular interactions with a variety of hazardous chemicals including explosives, chemical agents, narcotics, and toxic industrial chemicals. Applications of functionalized sorbent polymers include preconcentrator devices, SPME fibers, membrane introduction systems, chromatographic stationary phases and coatings for chemical sensors. One common feature of a wide range of hazardous chemicals is their hydrogen bond (h-b) basicity. In this work, we report on the synthesis and characterization of a h-b acidic hyperbranched carbosilane fluoroalcohol based sorbent polymer (poly(methyldi(1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypent-4-enyl)silane; HCSFA2), which is suitable for sorbing these hazardous h-b basic analytes. Multiple batches of HCSFA2 were characterized with routine composition, spectroscopic, thermal analysis, and inverse gas chromatography (iGC) to evaluate polymer physicochemical properties. In comparison with previously developed h-b acidic polymers (e.g., FPOL and SXFA), HCSFA2 exhibits a sorption improvement of 10-15 fold for h-b basic analytes. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3000-3009, 2010

Infrared spectroscopy for chemical agent detection using tailored hypersorbent materials

“…6, a feature common to many of the analytes is the negative dip at 1120 cm-1. This corresponds to a shift of one of the CF bands in the HCSFA2 6 . The third type of spectral feature in the differential absorbance arises from resonances of the analyte itself that are modified by interacting with the HCSFA2 sorbent.…”

“…Different sorbent polymers have been developed at the NRL to provide complementary OH bonding structures to the Gphosphonate nerve agents, and provide large gas-polymer partition coefficients 6 . With optical spectroscopy, this has the benefit of reducing the concentration of interferents in the polymer, producing stronger differential absorption peaks from nerve gas simulants than from interferents at much higher concentration in the ambient.…”

“…The use of sorbent materials, specifically developed at NRL to provide complementary hydrogen bond properties to nerve agents, provides a path to perform IR spectroscopy in a small volume. Polymers such as HCSFA2, selectively sorb and concentrate molecules of interest from air to amplify signal responses in IR spectroscopy 6 . The concentration of hazardous chemicals in the sorbent polymer is several orders of magnitude higher than that in the ambient.…”

Nanophotonic waveguides for chip-scale raman spectroscopy: Theoretical considerations

“…for condensed-phase sensing) or as a sorbent material for gas-phase sensing. 3,4 This calculation takes into account the modification of the molecular scattering rate due to the presence of guided modes, as well as the overlap of the analyte molecules with the evanescent field of the waveguide. We conclude by comparing our calculated Raman scattering effiiciency with the efficiency deduced from measurements of trace-gas scattering in sorbent-coated silicon nitride (SiN) waveguides.…”

Solutochromic Molecular Spectroscopy with a Reference Hydrogen-Bond Acid Dendrimer

“…With the general absence of suitable commercial HB acidic materials for these applications, a number of researchers at NRL and elsewhere have developed a range of HB acidic materials based on sorbent polymers which incorporate hydroxyl functional groups in their repeat unit, with suitably positioned fluorine atoms used to augment the HB acidity and reduce HB basicity. Ether-linked structures were first employed, followed by hydrocarbon based backbone polymers, and then by a range of functionalized polysiloxanes, leading to more recent work with various functionalized HB acidic polycarbosilanes [6].…”