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Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS)

Yao, Mengmeng
http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345

Abstract Details

2014, Master of Science, University of Akron, Polymer Science.
ABSTRACT Surface layer matrix-assisted laser desorption ionization time-of-flight mass spectrometry (SL-MALDI-TOF MS) is a new technique to determine the surface composition of a blend film.1 The motivation of developing SL-MALDI-TOF MS is the need to measure the composition of polymer blend surfaces without having to label one component and being able to distinguish components having the same repeat, but different architectures. Polystyrene is readily ionized by MALDI making it a good candidate for this study. In this project, quantitative analyses were performed as a function of molecular weight using polystyrene standards. Such studies can be extended to similar analyses on other polymers. The first objective of this MS project was to establish the upper molecular weight (M) limit for the determination of surface composition of a polymer blend using SL-MALDI-TOF MS techniques and the variation in yield from the surface with M. We found that molecular weights from 2 to 21k could be studied. Longer polymer chains were harder to ionize, and were detected with lower efficiency. Also, the spectra of the polymer films were less resolved at higher molecular weights due to use of linear mode time-of-flight (TOF) mass analyzer and higher electronic noise. The second objective was to demonstrate the applicability of SL-MALDI-TOF MS for the measurement of surface composition of binary blends by determining the dependence of the degree of surface enrichment in isotopic blends of hydrogenous linear polystyrene (hPS) and deuterated linear polystyrene (dPS) on molecular weight. The apparent mole fraction is most accurate for blend sample with mole fraction composition near 0.5 hPS. The inaccuracy in determining the mole fraction of the surface of the film when the blend composition is far from 0.5 can be explained by the electronic noise in the spectra. The electronic noise had a very pronounced effect on the peak shape of the component with the smaller mole fraction which made the calculation of peak area inaccurate. Furthermore, SL-MALDI-TOF MS becomes less accurate as molecular weight increases. This additional loss of accuracy can be attributed to the increased difficulty of ionization and loss of resolution, affecting the ease with which peaks are distinguishable from one another.
Mark Foster (Advisor)
Mesfin Tsige (Committee Member)
88 p.
Materials Science; Molecular Chemistry; Polymers
SL-MALDI-TOF MS, Isotopic blend,surface composition

Recommended Citations

Citations

  • Yao, M. (2014). Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS) [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345

    APA Style (7th edition)

  • Yao, Mengmeng. Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS) . 2014. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345.

    MLA Style (8th edition)

  • Yao, Mengmeng. "Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS) ." Master's thesis, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.