Tryptamine was evaluated as a reagent for derivatizing hexamethylene diisocyanate (HDI) monomer and oligomers during actual spray-painting operations. In one side-by-side sampling study, an impinger filled with 1-(2-methoxyphenyl)piperazine in toluene was compared with a second impinger filled with tryptamine in dimethyl sulfoxide (DMSO). The amount of HDI monomer obtained was below the limit of quantification for both impingers. The amount of HDI oligomer obtained when using 1-(2-methoxyphenyl)piperazine in toluene was comparable to the amount obtained when using an impinger filled with tryptamine in DMSO. In a second side-by-side sampling study, a tryptamine-coated XAD-2 resin was used as a sorbent. The relative collection efficiency of the tryptamine-coated XAD-2 resin was on average 60% of the value obtained using an impinger filled with tryptamine in DMSO. The results indicate that using an impinger filled with tryptamine in DMSO gives higher concentrations of isocyanate than a tryptamine-coated XAD-2 sorbent for HDI monomer and oligomer.
XPS studies of Cu(I)hfac(COD)adsorbed on clean and alumina-modified Teflon-AF surfaces show that on the clean polymer surface, Cu(0) formation occurs between 300 K and 600 K in UHV. The corresponding reduction is hindered by the presence of an alumina adlayer. In addition, the Cu Auger kinetic energies indicate the formation of nanoparticles on the alumina surface at both 300 K and 600 K. Annealing from 300 K to 600 K results in a ∼4 eV shift of the Cu(2p) transitions to higher binding energies. These facts indicate that the Cu precursor reacts with the alumina surface and results in limited mobility and hindered Cu(I) to Cu(0) reduction on the modified polymer surface.
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