Following treatment of the printed cartridge with H2SO4-SO3 the material was analyzed by infrared spectroscopy (Figure ). When the untreated ABS cartridge was analyzed, the IR spectrum (Figure ) shows the expected absorbance bands for ABS polymer. This includes a weak nitrile CN stretch at 2200 cm -1 , the butadiene block C=C bond stretch at 1450 cm -1 , and the C=C bond stretching bands of the phenyl groups at 1500 and 1675 cm -1 . After functionalization, the sulfonylated material exhibits a dramatically different IR spectrum (Figure ). Although broad absorptions obscure some of the details of the spectrum, a broad band appears at 3500 cm -1 , a new strong broad absorption band is visible at 1700 cm -1 , and new bands appear in the 1000-1100 cm -1 range. Sulfonylated ABS-CF also shows these absorbances (Figure ). Similar bands are observed in the IR spectrum of Amberlyst-15, a commercially important acid catalyst prepared from sulfonylation of poly(divinylbenzene-co-styrene) resin (Figure ). In order to rule out the possibility that the H2SO4-SO3 treated ABS plug was not and no absorptions in the 1700 cm -1 region, 6 while the H2SO4-SO3 treated ABS and ABS-CF plugs exhibit several new absorption bands in the 1000-1300 cm -1 and 1700 cm -1 regions. Based on the differences in the IR spectra, these data are consistent with aromatic sulfonylation of the phenyl groups of the printed ABS plug.