Observation of low molecular weight poly(methylsilsesquioxane)s by graphite plate laser desorption/ionization time of-flight mass spectrometry

Mass spectra of polystyrene and poly(methylsilsesquioxane)(PMSSQ) derived from methyltriethoxysilane (MTES) were obtained in the 100-1000 Da range by laser desorption/ionization time-of-night mass spectrometry using a graphite plate without a matrix. Clean mass spectra were obtained without interference from carbon clusters or other low molecular weight compounds. Initial reaction products derived from condensation of partially hydrolyzed MTES were observed. Upon 30 min of heating at 30 degreesC, the ethoxy groups were fully hydrolyzed to hydroxy groups. Many PMSSQ species consistent with predictable polymerization reaction pathways involving intermolecular condensation and intramolecular dehydration were observed. Thus, laser desorption/ionization time-of-flight mass spectrometry using a graphite plate, without added matrix materials, is shown to provide valuable information on low molecular weight polymer not available by MALDI-TOF-MS.