• Analytical Science and Technology
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• v.8 no.4
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• pp.715-722
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• 1995

The structural characterization for series of polyesters has been done by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Polymer fragments and intact oligomers composed of large numbers of repeat units have been investigated. Transesterification of polyesters in trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CFA) was monitored and reaction products were identified using TOF-SIMS. The shapes and intensities of clusters in transesterification spectra show good agreement with the theoretical isotope pattern. TOF-SIMS spectra were used to obtain information about the progress of the transesterification reaction.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.89.1-89.1
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• 2011

The influence of potential and humidity on the electrochemical carbon corrosion in high temperature polymer electrolyte membrane fuel cells(HT-PEMFCs) is investigated by measuring $CO_2$ emission at different potentials for 30 min using on-line mass spectrometry. These results are compared with low tempterature polymer electrolyte membrane fuel cells(LT-PEMFCs) operated at lower temperature and higher humidity condition. Although the HT-PEMFC is operated at non humidified condition, the emitted $CO_2$ in the condition of HT-PEMFC is more than LT-PEMFC at the same potential in carbon corrosion test. Thus, carbon corrosion shows a stronger positive correlation with the cell temperature. In addition, the presence of a little amount of water activate electrochemical carbon corrosion considerably in HT-PEMFC. With increased carbon corrosion, changes in fuel cell electrochemical characteristics become more noticeable and thereby indicate that such corrosion considerably affects fuel cell durability.

• Polymer(Korea)
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• v.27 no.3
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• pp.271-274
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• 2003

A pyrolysis gas-chromatographic method (Py-GC) was utilized for the identification as well as the content measurement of textile materials. Py-GC was applied to natural cotton fiber, synthetic polyester fiber, and their blended fabrics. The characteristic peaks originated from thermally decomposed products were observed, and the area of peak increased with the content of polyester. The products of pyrolized polyester were identified as benzoic acid terephthalic acid, and vinyl benzoic acid, which were characterized by mass spectrometry. This analytic method of offered a quantitative means to identify the content of cotton and polyester.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.168-168
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• 1996

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.740-746
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• 2005

In this article, we report the tandem mass spectrometry investigations for the electron capture efficiencies of the protons belonging to the different locations (generations) in a poly(propylene imine) dendrimer with three layers of a repeat unit (named as the third generation dendrimer). The employed tandem mass spectrometry methods include SORI-CAD (sustained off-resonance irradiation collisional activation dissociation) and ECD(electron capture dissociation) mass spectrometry. We obtained SORI-CAD spectra for the dendrimer ions in the different charge states, ranging from 2+ to 4+. The analysis of fragmentation sites provides the information as to where the protons are distributed among various generations of the dendrimer. Based upon this, a new strategy to study the electron capture efficiencies of the protons is utilized to examine a new type of triplycharged ions by SORI-CAD, i.e., the 3+ ions generated from the charge reduction of the native 4+ ions by ECD: (M+4H)$^{4+}\;+\;e^-\;{\rightarrow}$ (M+4H)$^{3+\bullet}$ ${\rightarrow}\;({H^{\bullet}}_{ejected}$) + (M+3H)$^{3+}\;\rightarrow$ CAD. Interestingly, comparison of these four SORICAD spectra indicates that the proton distribution in the charge-reduced 3+ ions is very close to that in the native 4+ ions. It further suggests that in this synthetic polymer ($\sim$1.7 kDa) with an artificial architecture, the electron capture efficiencies of the protons are actually insensitive to where they are located in the molecule. This is somewhat contradictory to common expectations that the protons in the inner generations may not be well exposed to the incoming electron irradiation as much as the outer ones are, thus may be less efficient for electron capture. This finding may carry some implications for the case of medium sized peptide ions with similar masses, which are known to show no obvious site-specific fragmentations in ECD MS.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.203-203
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• 1999

Mass spectrometry technique provides the molecular weight distribution, data on the sequence of repeat units, polymer additives, and impurities, and structural information. time-of-Flight secondary Ion Mass Spectrometry (TOF-SIMS) has been used for structural characterization of various polymers1-2. the masses of repeat units and terminal groups and molecular weight distributions of polymers have been determined from their TOF-SIMS spectra. TOF-SMIS provides good sensitivity and structural specificity for high mass ions so that intact oligomers and large polymer fragments are observed. In this study, we investigated the detailed structural information on the oligomers and fragment ions of branched poly(1,3-butylene adipate) and branched poly[di(ethylene glycol) adipate] and the transesterification products of branched polyesters with trifluoroacetic acid or chloro difluoroacetic acid. Branched polyesters were chosen because they are important polymers but difficult to characterize; thus branched polyesters provide challanging test for TOF-SIMS. TOF-SIMS spectra of polyesters are obtained from thin polymer films cast from solution on a silver substrate. A good solvent for a polumer solution disrupts intermolecular forces between polymer chains but leaves the polumer intact. Transesterification reactions are potentially useful for characterization of high molecular weight and intractable polyesters. Transesterification products of polyesters and trifluoroacetic acid or an integral number of polyester repeat units and an additional diol. The progress of such reactions was monitored using peak intensities of reactants and products in TOF-SIMS spectra. The increasing abundance of tagged ions indicates that the reaction has progressed with time.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.263-271
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• 2017

The application of mass spectrometry to polymer science has rapidly increased since the development of MALDI-TOF MS. This review summarizes current polymer analysis methods using MALDI-TOF MS, which has been extensively applied to analyze the average molecular weight of biopolymers and synthetic polymers. Polymer sequences have also been analyzed to reveal the structures and composition of monomers. In addition, the analysis of unknown end-groups and the determination of polymer concentrations are very important applications. Hyphenated techniques using MALDI-tandem MS have been used for the analysis of fragmentation patterns and end-groups, and also the combination of SEC and MALDI-TOF MS techniques is recommended for the analysis of complex polymers. Moreover, MALDI-TOF MS has been utilized for the observation of polymer degradation. Ion mobility MS, TOF-SIMS, and MALDI-TOF-imaging are also emerging technologies for polymer characterization because of their ability to automatically fractionate and localize polymer samples. The determination of polymer characteristics and their relation to the material properties is one of the most important demands for polymer scientists; the development of software and instrument for higher molecular mass range (> 100 kD) will increase the applications of MALDI-TOF MS for polymer scientists.

• Analytical Science and Technology
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• v.8 no.4
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• pp.865-868
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• 1995

The method of matrix-assisted laser desorption ionization mass spectrometry has been used to solve some bioanalytical problems, which is difficult to analyse by general methods. For the selection of proper laser wavelength and matrices, eight matriees was used with laser wavelength of 226 and 355nm. The result shows that with wavelength of 355nm better results could be obtained with most of the matrices. The molecular weight of eytochrome C, which was seperated by gel electrophoresis and electro-blotted onto NC membrane is determined by MALDI. The accuracy is better than 0.1%, which is much higher than that of SDS-PAGE. Protein mixture extracted from crude peanut oil is directly determined by MALDI. The molecuiar weight of its three components are determined, and the result also demonstrated that these proteins are in free manner. As proteins arc in 2S bond, with the traditional method, SDS-PAGE, it is not able to decide whether protein exists in combination mode or in free manner. In the technique of two phase aquesous solution, which is used for separating biomaterials, water soluble polymers stained with dyes are used in this technique. By the use of MALDI the number or the dye molecules react with the polymer PEG molecule are determined, and that is difficult to determined by other methods.

• Archives of Pharmacal Research
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• v.27 no.1
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• pp.25-30
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• 2004

Combinatorial homoserine lactone mixtures and individual products were obtained from the methionine-functionalized resin in solid-phase synthesis. The four-step process consisting of a coupling step of an N-Fmoc-L-methionine, deprotection of N-Fmoc group, N-coupling with a carboxylic acid, and cleavage reaction through a polymer supported strategy is described. Gas chromatography-mass selective detector (GC-MSD) techniques provide the most powerful methods for identifying both the combinatorial mixtures and individual products.

• Fibers and Polymers
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• v.5 no.2
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• pp.83-88
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• 2004

In order to assess the potential of the hydroxy-containing polyamic acid (PHAA) synthesized from 3,3'-dihydroxy benzidine and pyromellitic dianhydride for a fire-safe polymer, the cyclization pathway of PHAA has been investigated using a model compound prepared from 2-aminophenol and phthalic anhydride. The reaction was monitored. by $^1{H-nuclear}$ magnetic resonance. N-(2-hydroxyphenyl) phthalamic acid is converted to N-(2-hydroxyphenyl) phthalimide at ca. 175$^{\circ}C$, showing endothermic reaction. The imide structure is rearranged to the benzoxazole structure over ca. $400^{\circ}C$. These results are similar with that of PHAA. According to pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) data, water and carbon dioxide are released during the cyclization and rearrangement reaction. One DMAc molecule is complexed with one carboxyl acid group in PHAA, which accelerates the imidization process to release more easily the flame retardant, water.