Isosteric heat of argon adsorbed on single-walled carbon nanotubes prepared by laser ablation.
ABSTRACT We have measured 21 adsorption isotherms for argon on single-walled carbon nanotubes produced by laser ablation. We explored temperatures between 40 and 153 K to obtain the coverage dependence of the isosteric heat of adsorption for films in the first and second layers. Our data are compared to results obtained in computer simulation studies and to data obtained in previous experimental investigations of this system.
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ABSTRACT: Three silicon and nitrogen-centered cyanate monomers tetrakis(4-cyanatophenyl)silane, tetrakis(4-cyanatobiphenyl)silane, and tris(4-cyanatobiphenyl)amine were designedand synthesized, which were then polymerized via thermal cyclotrimerization reaction to create highly porous cyanate resin networks with systematically varied nodes and linking struts. The chemical structures of monomers and polymers were confirmed by 1H NMR, FTIR, solid-state 13C CP/MAS NMR spectra, and elemental analysis. The products are amorphous with 5% weight-loss temperatures over 428 °C. The results based on N2 and CO2 adsorption isotherms show that the pores in these polymers mainly locate in the microporous region, and the BET surface areas are up to 960 m2 g–1, which is the highest value for the porous cyanate resin reported to date. The nitrogen- and oxygen-rich characteristics of cyanate resins lead to the networks strong affinity for CO2 and thereby high CO2 adsorption capacity of 11.1 wt % at 273 K and 1.0 bar. The adsorption behaviors of H2, CO2, benzene, n-hexane, and water vapors were investigated by correlating with the chemical composition and porosity parameters of the networks as well as the physicochemical nature of adsorbates.Macromolecules 06/2012; 45(12):5140–5150. · 5.93 Impact Factor
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ABSTRACT: Naphthalene was selected as a building block to prepare three polyimide networks with different topological structures via one-pot polycondensation from naphthalene-1,4,5,8-tetracarboxylic dianhydride with tetrakis(4-aminophenyl)methane, tris(4-aminophenyl)amine, and 1,3,5-tris(4-aminophenyl)benzene. The resultant polymers have moderately large BET surface areas with narrow pore size distribution at around 6 Å. Interestingly, it is found that they can uptake 90.5 wt % benzene vapor (298 K, 0.8 bar), and the separation factors of benzene over nitrogen, water, and cyclohexane are as high as 759.3, 40.3, and 13.8, respectively. The high adsorption capacity and selectivity of benzene vapor are attributed to the incorporation of large amount of naphthalene groups in the network since naphthalene is highly hydrophobic in nature and has strong π-electron-delocalization effect. On the other hand, the CO2 uptakes in polymers reach 12.3 wt % (273 K, 1 bar), and the adsorption curves are reversible. Moreover, the separation factors of CO2/N2 and CO2/CH4 are 88.6 and 12.9, respectively, superior to many other microporous organic polymers. The above experimental results were analyzed and explained with respect to the kinetic diameters, polarity, critical temperature of the vapors and gases, and the stereoconfiguration of net nodes, porous characteristics, and hydrophobic/hydrophilic nature of the pore walls of the microporous polyimides.The Journal of Physical Chemistry C 11/2013; 117(46):24428–24437. · 4.84 Impact Factor
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ABSTRACT: Micellles of poly(cyclohexyl metharylate)-block-poly(2-vinylpyridine) (PCMA-b-P2VP) block copolymer in methanol were used as nanoreactors to fabricate FeCl3 nanoparticles. Then the FeCl3-loaded micelles solution was used as an ink to print films with polydimethylsiloxane (PDMS) stamps, different morphologies of the FeCl3-loaded micellar films were left onto silicon substrates after printed. After removing the polymer by thermal decomposition, the left iron oxide cluster arrays on the substrate were used as catalysts for the growth of CNTs by the process of PECVD, where the CNTs uniformly distributed on the substrates according to the morphologies of patterned catalysts arrays. Moreover, with a pre-coating of aluminum oxide (Al2O3) layer onto silicon wafers, CNTs grew vertically onto the substrates with the catalyst nanoparticles, forming aligned and patterned structures.01/2009;