| Incorporation of amino acid pendant groups along the polyolefin backbone of acyclic diene metathesis (ADMET) polymers leads to the formation of chiral polymer structures with potential applications as biomaterials. On the other hand, small changes in the chemical structure of ethylene oxide/propylene oxide (EO/PO) copolymers induce variations in their properties, and in turn, allow for their use as surface-active agents, detergents, foams, lubricants, etc. As a result, studying structure-property relationships in these polymers is important and mass spectrometry characterization becomes an essential step in their analyses.;The goal of the research is structural characterization of a series of amino acid functionalized ADMET polymers and a set of two molecular weight versions of EO/PO copolymers. In addition to structural elucidation, the particular objectives of the mass spectrometry analyses target determination of the polymers' molecular weight distribution and polidispersity index, confirmation of previous analytical data about possible isomerization taking place during ADMET polymerization, correlation of the structure of the ADMET polymers to the polymerization mechanism, sequencing of the EO/PO copolymers. To achieve these objectives, MALDI (matrix-assisted laser/desorption ionization) and DIOS (desorption/ionization on porous silicon) were interfaced either to the time-of-flight (TOF) or the Fourier transform ion cyclotron resonance (FTICR) mass analyzer and used for polymer analyses.;The mass spectrometry data of the amino acid ADMET polymers indicate that isomerization occurs as a side reaction of metathesis polymerization with the second generation Grubbs' catalyst at elevated temperatures; consequently, precise structural control of the polymers under these conditions is impossible. In addition, the data show that due to their different structural characteristics, the olefins display different selectivity towards main metathesis or isomerized products.;For EO/PO mass analyses, only the resolving power of the FTICR mass analyzer provides resolution and accuracy that are high enough to achieve fine structural characterization of the copolymers; overlapping oliogmeric peaks in the low resolution MALDI-TOF spectra prevent accurate determination of the unknown oligomer end groups and of the exact number of the EO and PO units in each oligomeric chain. |
