Browsing by Author "Fox, BL"

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    Dispersing single-walled carbon nanotubes in ionic liquids: a quantitative analysis
    (Royal Society of Chemistry, 2013-08-15) Hameed, N; Church, JS; Salim, NV; Hanley, TL; Amini, A; Fox, BL
    The efficiency of various ionic liquids, specifically the 1-butyl-3-methylimidazolium tetrafluoroborate, hexafluorophosphate, chloride and dicyanamide salts, in dispersing single walled carbon nanotubes has been examined. The SWCNTs were dispersed in the ILs at varying concentrations by grinding. All of the ILs were found to be effective dispersants for nanotubes and quantitative evidences including X-ray scattering, Raman spectroscopy and UV-visible spectroscopy unambiguously showed that BMIM[BF4] is the most efficient IL while BMIM[DCA] is the least effective IL. A quantitative analysis of the interactions between SWCNTs and ionic liquids by analyzing their scattering and spectral features is put forth.© 2013, The Royal Society of Chemistry.
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    Hydrogen bonding interactions in poly(ε-caprolactone–dimethyl siloxane–ε-caprolactone)/poly(hydroxyether of bisphenol A) triblock copolymer/homopolymer blends and the effect on crystallization, microphase separation and self-assembly
    (Elsevier B.V., 2015-06-01) Salim, NV; Fox, BL; Hanley, TL
    This study investigated the self-assembled microphase separated morphologies that are obtained in bulk, by the complexation of a semicrystalline poly(ε-caprolactone–dimethyl siloxane–ε-caprolactone) (PCL–PDMS–PCL) triblock copolymer and a homopolymer, poly(hydroxyether of bisphenol A) (PH) in tetrahydrofuran (THF). In these blends, microphase separation takes place due to the disparity in intermolecular interactions; specifically, the homopolymer interacts with PCL blocks through hydrogen bonding interactions. The crystallization, microphase separation and crystalline structures of a triblock copolymer/homopolymer blends were investigated. The phase behavior of the complexes was investigated using small-angle X-ray scattering and transmission electron microscopy. At low PH concentrations, PCL interacts relatively weakly with PH, whereas in complexes containing more than 50 wt% PH, the PCL block interacts significantly with PH, leading to the formation of composition-dependent nanostructures. SAXS and TEM results indicate that the lamellar morphology of neat PCL–PDMS–PCL triblock copolymer changes into disordered structures at 40–60 wt% PH. Spherical microdomains were obtained in the order of 40–50 nm in complexes with 80 wt% PH. At this concentration, the complexes show a completely homogenous phase of PH/PCL, with phase-separated spherical PDMS domains. The formation of these nanostructures and changes in morphology depends on the strength of hydrogen bonding between PH/PCL blocks and also the phase separated PDMS blocks. © 2015 Elsevier Ltd.
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    Individual dispersion of carbon nanotubes in epoxy via a novel dispersion-curing approach using ionic liquids
    (Royal Society of Chemistry, 2013-01-01) Hameed, N; Salim, NV; Hanley, TL; Sona, M; Fox, BL; Guo, Q
    The effective dispersion of carbon nanotubes (CNTs) in a thermoset was achieved using ionic liquid as the dispersion-curing agent. We preferentially dispersed multiwalled carbon nanotubes (MWCNTs) down to individual tube levels in epoxy resin. Here the dispersion is ruled by the depletion of physical bundles within the MWCNT networks, for which molecular ordering of ionic liquids is considered responsible. The quantitative analyses using ultra small angle X-ray scattering (USAXS) confirmed the dispersion of individual MWCNTs in the matrix. The distance between the dispersed nanotubes was calculated at different nanotube loadings using the power law fitting of the USAXS data. The fine dispersion and subsequent curing, both controlled by ionic liquid, lead to composites with substantially enhanced fracture mechanical and thermomechanical properties with no reduction in thermal properties. Merging processing techniques of nanocomposites with ionic liquid for efficient dispersion of nanotubes and preferential curing of thermosets facilitates the development of new, high performance materials. © 2013, Royal Society of Chemistry