Abstract
Chemical structures in acrylate-type ultra violet (UV) -cured resins were characterized using specific sample decomposition. At first the cured resin sample was analyzed by pyrolysis-gas chromatography (Py-GC) in the presence of organic alkali, tetramethylammonium hydroxide (TMAH) . A series of products, not only those of the constituent monomers and prepolymers, but also methyl acrylate (MA) and its oligomers (up to hexamers) reflecting the cross-linking sequences, which were formed through thermally assisted hydrolysis and methylation selectively occurred at ester linkages in the UVcured resins, were observed in the pyrograms. These products were interpreted in terms of the chemical composition and molecular weight of the constituent monomers (prepolymers) , their double bond conversion in curing, and the sequence distributions of network junctions. Moreover, the UV cured resins were also characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis of the samples. The methanolysis products were fractionated by size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The observed distributions of the decomposition products suggested that the network junctions in the UV-cured resin were composed of up to around 2,000 acrylate units.
