Compositional Analysis of the High Molecular Weight Ethylene Oxide-Propylene-Oxide Copolymer by MALDI Mass Spectrometry (original) (raw)
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The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.
Rapid Communications in Mass Spectrometry, 2007
The results of copolymer characterization by coupling of chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) techniques and subsequent calculation of copolymer composition using a novel software tool 'MassChrom2D' are presented. For high-resolution mass analysis copolymer samples were fractionated by means of liquid adsorption chromatography (LAC). These fractions were investigated off-line by MALDI-TOF MS. Various mono-n-butyl ethers of polyethylene oxide-polypropylene oxide copolymers (PEOco-PPO) were investigated. As well as the copolymer composition presented in two-dimensional plots, the applied approach can give additional hints on specific structure-dependent separation conditions in chromatography. S. M. Weidner et al. Figure 11. MALDI-TOF MS/MS spectrum recorded for a precursor ion at m/z 2216.4 of a PEO-co-PPO polymer after chromatographic separation (top) and sections showing EO (middle) and PO distributions (bottom).
Analysis of copolymers by laser desorption fourier transform mass spectrometry
Journal of the American Society for Mass Spectrometry, 1990
A series of methylmethacrylatelbutylacrylate, methylmethacrylatelstyrene, and poly-(ethylene glycol)lpoly(propylene glycol) copolymers were analyzed by laser desorption Fourier transform mass spectrometry. Molecular weight distributions and overall copolymer compositions were determined. Typical spectra arise from a distribution of alkali metal cationized oligomer ions reflecting copolymer composition. Number-and weight-average molecular weights were calculated for each category of copolymer series as well as for overall copolymer mixtures. In addition, mass spectra were analyzed to estimate copolymer monomer contributions; these results were compared with manufacturer feed mix ratios as a test of the relative accuracy of the analysis. Although a dual-cell Fourier transform mass spectrometer was used, all copolymer analyses reported were carried out as single (source) cell measurements to ensure that no mass discrimination would occur. A series of Fourier transform mass spectrometry dual-cell experiments also were performed to evaluate the effect of ion transfer time on molecular weight averages and compositions. As expected, mass discrimination occurred when short transfer times and analyzer cell detection were employed. Under these conditions, molecular weight averages varied by more than 50% from values obtained in the single-cell measurements. (J Am Sot Mass Spectrum 1990, I, 66-71)
Macromolecular Research, 2003
A poly(ethylene oxide)-b-poly(L-lactide) diblock copolymer (PEO-b-PLLA) is characterized by matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and a block length distribution map is constructed. Although the MALDI-TOF mass spectrum of PEO-b-PLLA is very complicated, most of the polymer species were identified by isolating the overlapped isotope patterns and by fitting the overlapped peaks to the Schulz-Zimm distribution function. Reconstructed MALDI-TOF MS spectrum was nearly identical to the measured spectrum and this method shows its potential to be developed as an easy and fast analysis method of low molecular weight block copolymers.
Analytical Chemistry, 2008
Complex copolymers are heated to slowly increasing temperatures on a direct probe (DP) inside the plasma of the atmospheric pressure chemical ionization (APCI) source of a quadrupole ion trap. Slow heating allows for temporal separation of the thermal degradation products according to the stabilities of the bonds being cleaved. The products released from the DP are identified in situ by APCI mass spectrometry and tandem mass spectrometry. DP-APCI experiments on amphiphilic copolymers provide conclusive information about the nature of the hydrophobic and hydrophilic components present and can readily distinguish between copolymers with different comonomer compositions as well as between cross-linked copolymers and copolymer blends with similar physical properties. The dependence of DP-APCI mass spectra on temperature additionally reveals information about the thermal stability of the different domains within a copolymer. Electrospray ionization (ESI) 1 and matrix-assisted laser desorption/ionization (MALDI) 2,3 have made it possible to form intact gas-phase ions from most classes of synthetic polymers, enabling mass spectrometry (MS) analyses on such macromolecules. 4-20 MS experiments provide the masses of the individual oligomers contained in a polymer, from which important compositional and structural information about the polymer can be deduced, for example, its (co)monomer composition, end groups, compositional heterogeneity, and molecular weight distribution. Still, numerous synthetic polymers designed for important industrial or biomedical applications cannot be analyzed by MS, because they are too large or too polar to be dissolved (for ESI) or desorbed (for MALDI), or they are unable to form gas-phase ions due to the lack of functional groups that can attract and bind a charged particle, such as a proton or metal cation. Fortunately, most large or unionizable polymers become amenable to MS analysis by pyrolysis, i.e., thermal degradation. 9,21-30 Depending on the thermal stability of the polymer and the temperature used (typically within 150-1000°C), pyrolysis leads either to small fragments that can be ionized by electron ionization, chemical ionization (CI), field ionization, or photoionization, or to higher-mass pyrolyzates that can be subjected to ESI, MALDI, or both. The resulting mass spectra unveil the composition of the polymer sample. Molecular weight information is lost, but information about the thermal stability and degradation pathways of the polymer is gained. Rapid heating of the sample to a high temperature, via hightemperature Curie-point or resistive heating flash pyrolysis,
Structural characterization of polyester copolymers by MALDI mass spectrometry
Progress in Organic Coatings, 2002
A polyester copolymer is produced by step-growth polymerization of neopentyl glycol (50 mol%), trimethylol propane (1%), terephthalic acid (45%) and adipic acid (5%) and its microstructure is characterized by gel permeation chromatography and matrix-assisted laser desorption ionization mass and tandem mass spectrometry. The combination of these analytical methods is shown to yield detailed insight about the composition, end groups, molecular weight, and sequence of the product.
Journal of Applied Polymer Science, 2018
ABSTACT: Poly(styrene-co-4-vinylpyridine) random copolymers with different molar composition were synthesized by nitroxidemediated controlled-radical polymerization using 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) as a mediator. We record the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) spectra under various conditions, and we find (at last) that they show mostly intact ions [using 2(-4-hydroxyphenylazo-)benzoic acid as MALDI matrix]. Spectra are highly resolved, and thus they allow for the determination of all end-groups, even some less-abundant ones. Spectra are dominated by intact "dormant" copolymer chains terminated with TIPNO at one end and with (4-Bromo-phenyl)ethyl group (starting fragment) at the other one. Applying the mass analysis of copolymers (MACO) statistical model to the spectra, we show that the MACO/MALDI-TOF mass spectrometry (MS) analysis can be successfully applied to copolymers having a difference between the mass of the comonomers as small as 1 g mol −1 (the styrene and 4-vinylpyridine units are 104.15 and 105.15 g/mol, respectively), which results in overlapping isotopic patterns. The results are accurate: chemical composition evaluated by means of MS agrees with that calculated by 1 H-nuclear magnetic resonance, for all copolymers investigated. This analytical method allows to extract detailed information on the composition of the copolymer samples and their structure. Glass transition temperatures of copolymers were also determined by differential scanning calorimetry.
Macromolecules, 1995
Octafunctionalized spherosilsesquioxanes (Q 8 M 8 H), decorated with Si−H functions, could be used to design, by coupling via hydrosilylation with α-methoxy-ω-undecenyl poly(ethylene oxide)s (PEOs), organic− inorganic nanocomposite structures. 1 H, 13 C, and 29 Si NMR; size exclusion chromatography; and Fourier transfrom infrared spectroscopy were used to follow the grafting reaction and determine the molar mass and the functionality of the different species. Hybrid star-shaped poly(ethylene oxide)s of precise molar mass and functionality could be isolated by fractional precipitation of the raw reaction product. Absolute molar masses of the purified star-shaped PEOs, calculated with the assumption of a functionality of 8, were comparable when measured by light scattering in methanol and by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Small-angle X-ray scattering was employed to determine their molecular and structural characteristics, representing the versatility and innovative aspect to this study. Both differential scanning calorimetry and optical microscopy were utilized to elaborate and analyze the thermal properties and crystallization, respectively, of the hybrid stars. Further ongoing work is being carried out currently to investigate and foresee the use of longer PEO branches onto the core.
Journal of the American Society for Mass Spectrometry, 1997
A quick and effective sample preparation is demonstrated for matrix-assisted laser desorption/ionization (MALDI) analysis of nonpolar polymers. Polyisoprene, polystyrene, and polybutadiene polymers were investigated by using as matrix a 2,5-dihydroxybenzoic acid and silver nitrate combination. Silver cationized oligomers produce useful spectra that can be signal averaged to characterize polymer distributions extending up to 6000 u by using a 3-T Fourier transform mass spectrometer. Because an electrostatic ion deceleration protocol was used to extend the mass range, trapping discrimination is shown to exist for molecular weight distributions broader than about 2500 u. However, an integral procedure can be used to reconstruct the true polymer profiles through co-addition of signal transients obtained by using various gated deceleration times. For polymers with narrower mass distributions, silver cationization along with signal averaging provides rapid and accurate polymer characterization for nonpolar polymer systems by using standard MALDI Fourier transform mass spectrometry instrumentation.