Direct characterization of polyurethanes and additives by atmospheric solid analysis probe with time-of-flight mass spectrometry (ASAP-TOF-MS)
Abstract
Because of the wide range of formulations, polyurethanes (PURs) are among the most used copolymers. According to their applications, the nature and concentration of the monomers, as well as the additives, are adjusted. As copolymer, this material is difficult to characterize directly by mass spectrometry without sample pretreatment. In this work, atmospheric solid analysis probe mass spectrometry (ASAP-MS) is used to characterize model and commercial PURs with different formulations. Application of a temperature gradient over the ASAP probe allows a soft vaporization of all sample components: additives are detected at lower gas temperature, whereas the polymer is detected at higher gas temperature. Thus, a temporal separation of the molecules as a function of their volatilization and/or degradation temperature is observed. The vaporized products are identified by ASAP thanks to pyrolysis, but also by low energy source fragmentation observed during the analysis. Thus, complete analysis of PURs with only a single time-of-flight (TOF) mass analyzer is realized. The ability of ASAP-MS for differentiation of different chemical structures of PURs (polyester and polyether based PURs) is demonstrated; the main advantage of this technique being that the analysis is performed in one step, directly on the crude polymer.