|Characterization of Cross-linking Structure in Cross-linking Polymers using Specific Decomposition of Samples
Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, Japan
Nippon Gomu Kyokaishi,(2007),80(7),254-259 General Review in Japanese
Cross-linking structure of cross-linking polymers, especially for acrylate-type ultraviolet (UV)-cured resin, was characterized using specific decomposition methods. 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 methyl acrylate (MA) oligomers (up to hexamers) were observed in the pyrograms, which were formed through thermally assisted hydrolysis and methylation selectively occurred at ester linkages in the UV-cured resin.
Moreover, acrylate-type UV cured resins were also characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis of the samples. The MALDI mass spectrum of the methanolysis products contained a series of peaks related to MA oligomers up to around 50-mers, which cannot be observed by Py-GC in the presence of TMAH. Furthermore, the methanolysis products were fractionated by size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The MALDI mass spectrum of the highest molar mass fraction showed a broad peak up to m/z ca. 180,000. 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.
Cross-linking Polymer, Cross-linking Structure, Pyrolysis-gas Chromatography, Tetramethylammonium Hydroxide, Supercritical Methanolysis, Acrylate-type Ultraviolet Cured Resin, Matrix Assisted Laser Desorption / Ionization - Mass Spectrometry, Size Exclusion Chromatographic Fractionation