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Temperature-programmed desorption experiments show that acetone chemisorbs on nanotubes while physisorption occurs on graphite. Computed high binding energies for chemisorption using hybrid quantum mechanical and semiempirical calculations are in good agreement with the experimental thermal desorption data. The strong chemical interactions between acetone and the nanotube surface are established as being due to the effects of curvature and topological defects.

We report here the first use of a dendrimer for catalysis.The rates of unimolecular decarboxylation of 6-nitrobenzisoxazole-3-carboxylate (1; eq 1) and bimolecular hydrolysis 02N of p-nitrophenyl diphenyl phosphate (2) catalyzed by o-iodosobenzoate ion (IBA; eq 2) are accelerated by the quaternary ammonium ion dendrimer PE-TMA36.The catalytic effect of PE-TMA36 is analogous to that of other colloidal and polymeric quaternary ammonium ions. Micelles,1®4 microemulsions,la~d*i bilayer vesicles, polyelectrolytes,2 latexes,3 and anion-exchange resins4 often enhance rates of chemical reactions in aqueous mixtures. The rate enhancements may arise from high concentrations of reactants bound to the association colloid or polymer, to greater reactivity of the bound reactant than in water, or to both. For example, the observed rate constants of the unimolecular decarboxylation of 1 range from 220 to 10 500 times greater than in water using hydrophilic poly[(styrylmethyl)trimethylammonium] ion and lipophilic poly[(styrylmethyl)tributylammonium] ion latexes, respectively, and the intraparticle rate constants are 310 and 21 000times greater at ambient temperature.3b

The impact of grazing cattle (Bostauras) on water quality has been the subject of considerable interest as water quality standards become more restrictive. Benthic sediments have been found to harbor significantly higher concentrations of enteric bacteria than the overlying water. In this study, the survival of fecal coliform and fecal streptococci organisms was demonstrated to be significantly longer in sediment laden waters than in those without sediment and further the survival was longer in the sediment-laden waters than in a supernatant from that same sediment suspended in water. Fecal coliform and fecal streptococci bacteria revealed half-lives from II to 30 d and 9 to 17 d, respectively when incubated with sediment. This is longer than when they are similarly incubated without sediment.

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A solvent-free mechanochemical route for the synthesis of polyaniline has been developed. Reactions between anilinium salts, such as anilinium chloride, anilinium sulfate, and anilinium camphorsulfonic acid and the oxidant, ammonium peroxydisulfate, result in polyaniline formation on ball-milling the reactants. Spectroscopic studies indicate that polyaniline is formed in its doped, conductive emeraldine oxidation state. By varying the aniline-to-oxidant ratio, a yield of up to 65% can be achieved. The polyaniline has a relatively high surface area of 69.7 m 2 /g using the Brunauer-Emmett-Teller method. A typical bimodal molecular weight distribution is observed for the polyaniline product. Resistance measurements indicate that 1 h is sufficient for the solid-state reactions to reach completion.

The chemical changes in poly(methylmethacrylate) (PMMA) caused by irradiation with deep ultraviolet (UV), x-ray, electron, and proton beams were studied by gel permeation chromatography, Fourier-transform infrared, and UV spectroscopy. The quantitative analysis of spectroscopic changes (Beer’s law) demonstrated a 1:1 correspondence between the disappearance of ester groups and the generation of double bonds in the polymer chain by all types of radiation. The ratio of main chain scission to changes in the number of ester groups and unsaturated bonds was compared to determine the characteristics of degradation of PMMA by the different types of radiation. This ratio for deep UV data was very close to the quantum yield of main chain scission of PMMA as reported in the literature. High-energy radiation was ∼10× more efficient than deep UV in causing main chain scission with removal of fewer ester groups. Protons induced more main chain scission than electrons. X-ray irradiation was the most efficient at causing main chain scission of the four different types of radiation.

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