No abstract

Copolymers of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMAEMA) and ethylene glycol dimethacrylate (EGDMA) were synthesized via atom transfer radical polymerization using ethyl 2‐bromoisobutyrate as the initiator, Cu(I)Br as the catalyst, and 1,1,4,7,10,10‐hexamethyltriethylene tetramine as the ligand. At low crosslinker levels, the polymerizations followed the first‐order kinetics. However, when the crosslinker level was above 10 mol %, the ln([M]0/[M]) versus time curves showed deceleration at medium conversions because of the higher reactivity of EGDMA than that of DMAEMA. An acceleration at high conversions was also observed and probably caused by the diffusion limitations of catalyst/ligand complex in the polymer network. The hydrogels were characterized by swelling experiments, and the sol polymers were characterized by the size exclusion chromatographic technique to determine the number‐average molecular weight and polydispersity. The gel data were analyzed and, via a comparison to Flory's gelation theory, found to be more homogeneous than similar hydrogels prepared by conventional free‐radical polymerization methods. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3780–3788, 2001

No abstract

Low-cost anthracite was used as the raw material for preparing microporosity controlled activated carbons by KOH activation. The adsorption characteristics of methane onto activated carbon were measured at 298 K and pressures up to 3.5 MPa by a volumetric method. The experimental data were fitted to the Dubinin–Astakhov model, and relative deviations of better than 0.1 % were obtained. Three main factors were suggested, accounting for the higher methane uptake. It was revealed that better methane uptake is dependent on larger micropore volume and specific surface area. When the micropore volume and surface area of two samples are similar, the activated carbon possessing a narrower micropore size distribution performed higher methane uptake. The relationship between the surface coverage (C/C 0) and the isosteric heat of adsorption confirmed that the heterogeneities of the as-obtained samples was a main factor influencing the methane adsorption at a surface coverage lower than 0.7. The activated carbon possessing higher heterogeneity deserved better methane uptake. The kinetics of methane adsorption on five activated carbons obeyed the pseudosecond-order equation very well under current experimental conditions (298 K, 0.28 MPa). The activated carbon displayed a faster adsorption rate and possessed a better adsorption capacity of methane.

The rational designed defect enriched N-doped nanocarbons present superior activity and stability for H2S selective oxidation.