Structural characterization of synthetic polymers and copolymers using multidimensional mass spectrometry interfaced with thermal degradation, liquid chromatography and/or ion mobility separation

摘要

This dissertation focuses on coupling mass spectrometry (MS) and tandem mass spectrometry (MS/MS) to thermal degradation, liquid chromatography (LC) and/or ion mobility (IM) spectrometry for the characterization of complex mixtures.;In chapter II, an introduction of the history and the principles of MS and LC are discussed. Chapter III illustrates the materials and instrumentation used to complete this dissertation.;Polyethers have been characterized utilizing MS/MS, as presented in Chapter IV and Chapter VI. Diblock copolymers of polyethylene oxide and polycaprolactone, PEO-b-PCL, have been characterized by matrix-assisted laser desorption/ionization quadrupole/time-of-flight mass spectrometry (MALDI-Q/ToF) and LC-MS/MS (Chapter V). Thermoplastic elastomers have been characterized by thermal degradation using an atmospheric solids analysis probe (ASAP) and ion mobility mass spectrometry (IM-MS), as discussed in Chapter VII. Interfacing separation techniques with mass spectrometry permitted the detection of species present with low concentration in complex materials and improved the sensitivity of MS.;In chapter IV, the fragmentation mechanisms in MS/MS experiments of cyclic and linear poly(ethylene oxide) macroinitiators are discussed. This study aimed at determining the influence of end groups on the fragmentation pathways. In the study reported in Chapter V, ultra high performance liquid chromatography (UHPLC) was interfaced with MS and MS/MS to achieve the separation and in-depth characterization and separation of amphiphilic diblock copolymers (PEO- b-PCL) in which the architecture of the PEO block is linear or cyclic. Applying UPLC-MS and UPLC-MS/MS provides fast accurate information about the number and type of the blocks in the copolymers. Chapter VI reports MS/MS and IM-MS analyses which were performed to elucidate the influence of molecular size and collision energy on the fragmentation pathways of polyethers subjected to collisionally activated dissociation. Survival yields and collision cross-sections were derived for several oligomers of polyethers by MS/MS and IM-MS, in order to understand their fragmentation energetics and fully characterize their structures. In Chapter VII, application of ASAP and IM separation were coupled with MS and MS/MS to characterize commercially available thermoplastic elastomers. These compounds are mainly composed of thermoplastic copolymers, but also contain additional chemicals to enhance their properties or to protect them from degradation. Using ASAP-IM-MS enables fast analysis, involving mild degradation at ASAP and subsequent characterization of the desorbates and pyrolyzates by IM-MS and MS/MS. Such multidimensional dispersion considerably simplifies the resulting spectra, permitting the conclusive separation and characterization of the multicomponent materials examined.;Chapter VIII summarizes the findings of this dissertation and is followed by appendices.