Mass Spectrometry in Polymer Chemistry E-Book

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 906

Veröffentlichungsjahr: 2012

Beschreibung

Combining an up-to-date insight into mass-spectrometric polymer analysis beyond MALDI with application details of the instrumentation, this is a balanced and thorough presentation of the most important and widely used mass-spectrometric methods. Written by the world's most proficient experts in the field, the book focuses on the latest developments, covering such technologies and applications as ionization protocols, tandem and liquid chromatography mass spectrometry, gas-phase ion-separation techniques and automated data processing. Chapters on sample preparation, polymer degradation and the usage of mass-spectrometric tools on an industrial scale round off the book. As a result, both entrants to the field and experienced researchers are able to choose the appropriate methods and instrumentations -- and to assess their respective strengths and limitations -- for the characterization of polymer compounds.

Leseprobe

Contents

Cover

Related Titles

Title Page

Copyright

List of Contributors

Introduction

References

Chapter 1: Mass Analysis

1.1 Introduction

1.2 Measures of Performance

1.3 Instrumentation

1.4 Instrumentation in Tandem and Multiple-Stage Mass Spectrometry

1.5 Conclusions and Outlook

References

Chapter 2: Ionization Techniques for Polymer Mass Spectrometry

2.1 Introduction

2.2 Small Molecule Ionization Era

2.3 Macromass Era of Ionization

2.4 Modern Era of Ionization Techniques

2.5 Conclusions

Acknowledgments

References

Chapter 3: Tandem Mass Spectrometry Analysis of Polymer Structures and Architectures

3.1 Introduction

3.2 Activation Methods

3.3 Instrumentation

3.4 Structural Information from MS2 Studies

3.5 Summary and Outlook

Acknowledgments

References

Chapter 4: Matrix-Assisted Inlet Ionization and Solvent-Free Gas-Phase Separation Using Ion Mobility Spectrometry for Imaging and Electron Transfer Dissociation Mass Spectrometry of Polymers

4.1 Overview

4.2 Introduction

4.3 New Sample Introduction Technologies

4.4 Fragmentation by ETD and CID

4.5 Surface Analyses by Imaging MS

4.6 Future Outlook

Acknowledgments

References

Chapter 5: Polymer MALDI Sample Preparation

5.1 Introduction

5.2 Roles of the Matrix

5.3 Choice of Matrix

5.4 Choice of the Solvent

5.5 Basic Solvent-Based Sample Preparation Recipe

5.6 Deposition Methods

5.7 Solvent-Free Sample Preparation

5.8 The Vortex Method

5.9 Matrix-to-Analyte Ratio

5.10 Salt-to-Analyte Ratio

5.11 Chromatography as Sample Preparation

5.12 Problems in MALDI Sample Preparation

5.13 Predicting MALDI Sample Preparation

5.14 Conclusions

Acknowledgments

References

Chapter 6: Surface Analysis and Imaging Techniques

6.1 Imaging Mass Spectrometry

6.2 Secondary Ion Mass Spectrometry

6.3 Matrix-Assisted Laser Desorption Ionization (MALDI)

6.4 Other Surface Mass Spectrometry Methods

6.5 Outlook

References

Chapter 7: Hyphenated Techniques

7.1 Introduction

7.2 Polymer Separation Techniques

7.3 Principles of Coupling: Transfer Devices

7.4 Examples

7.5 Conclusions

References

Chapter 8: Automated Data Processing and Quantification in Polymer Mass Spectrometry

8.1 Introduction

8.2 File and Data Formats

8.3 Optimization of Ionization Conditions

8.4 Automated Spectral Analysis and Data Reduction in MS1

8.5 Copolymer Analysis

8.6 Data Interpretation in MS/MS

8.7 Quantitative MS and the Determination of MMDs by MS

8.8 Conclusions and Outlook

References

Chapter 9: Comprehensive Copolymer Characterization

9.1 Introduction

9.2 Scope

9.3 Reviews

9.4 Soft Ionization Techniques

9.5 Separation Prior MS

9.6 Tandem MS (MS/MS)

9.7 Quantitative MS

9.8 Copolymers for Biological or (Bio)medical Application

9.9 Software Development

9.10 Summary and Outlook

References

Chapter 10: Elucidation of Reaction Mechanisms: Conventional Radical Polymerization

10.1 Introduction

10.2 Basic Principles and General Considerations

10.3 Initiation

10.4 Propagation

10.5 Termination

10.6 Chain Transfer

10.7 Emulsion Polymerization

10.8 Conclusion

References

Chapter 11: Elucidation of Reaction Mechanisms and Polymer Structure: Living/Controlled Radical Polymerization

11.1 Protocols Based on a Persistent Radical Effect (NMP, ATRP, and Related)

11.2 Protocols Based on Degenerative Chain Transfer (RAFT, MADIX)

11.3 Protocols based on CCT

11.4 Novel and Minor Protocols

11.5 Conclusions

References

Chapter 12: Elucidation of Reaction Mechanisms: Other Polymerization Mechanisms

12.1 Introduction

12.2 Ring-Opening Polymerization Mechanisms of Cyclic Ethers

12.3 Ring-Opening Polymerization Mechanisms of Cyclic Esters and Carbonates

12.4 Ring-Opening Metathesis Polymerization

12.5 Mechanisms of Step-Growth Polymerization

12.6 Concluding Remarks

References

Chapter 13: Polymer Degradation

13.1 Introduction

13.2 Thermal and Thermo-Oxidative Degradation

13.3 Photolysis and Photooxidation

13.4 Biodegradation

13.5 Other Degradation Processes

13.6 Conclusions

References

Chapter 14: Outlook

Index

Related Titles

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List of Contributors

Grayna AdamusPolish Academy of SciencesCenter of Polymer and Carbon Materials34 M. Curie-Sklodowska Street41-800 ZabrzePoland

Christopher Barner-KowollikKarlsruhe Institute of Technology (KIT)Institut für Technische Chemie und PolymerchemieMacromolecular ChemistryEngesserstr. 1876128 KarlsruheGermany

Stephen J. BlanksbySchool of ChemistryUniversity of WollongongWollongong, NSW 2522Australia

Michael BubackGeorg-August-Universität GÖttingenInstitut für Physikalische ChemieTammannstr. 637077 GÖttingenGermany

Sabrina CarroccioNational Research Council (CNR)Institute of Chemistry and Technology of Polymers (ICTP)Via Paolo Gaifami 1895126 CataniaItaly

Anna C. CreceliusFriedrich-Schiller-University JenaLaboratory of Organic and Macromolecular Chemistry (IOMC)Humboldtstr. 1007743 JenaGermany

Guillaume DelaittreKarlsruhe Institute of Technology (KIT)Institut für Technische Chemie und PolymerchemieMacromolecular ChemistryEngesserstr. 1876128 KarlsruheGermany

Jana FalkenhagenBundesanstalt für Materialforschung und -prüfung (BAM)Federal Institute for Materials Research and TestingRichard-Willstätter-Strasse 1112489 BerlinGermany

Anthony P. GiesVanderbilt UniversityDepartment of Chemistry7330 Stevenson CenterStation B 351822Nashville, TN 37235USA

Till GruendlingKarlsruhe Institute of Technology (KIT)Institut für Technische Chemie und PolymerchemieMacromolecular ChemistryEngesserstr. 1876128 KarlsruheGermany

Charles M. GuttmanNational Institute of Standards and TechnologyPolymers DivisionGaithersburg, MD 20899USA

Scott D. HantonIntertek ASA7201 Hamilton Blvd. RD1, Dock #5Allentown, PA 18195USA

Gene Hart-SmithSchool of Biotechnology and Biomolecular SciencesUniversity of New South WalesSydney, NSW 2052Australia

Anthony J. KearsleyNational Institute of Standards and TechnologyApplied and Computational Mathematics DivisionGaithersburg, MD 20899USA

Marek KowalczukPolish Academy of SciencesCenter of Polymer and Carbon Materials34 M. Curie-Sklodowska Street41-800 ZabrzePoland

Christopher B. LietzWayne State UniversityDepartment of Chemistry5101 Cass AveDetroit, MI 48202USA

Christine M. MahoneyNational Institute of Standards and TechnologyMaterial Measurement LaboratorySurface and Microanalysis Science Division100 Bureau Drive, Mail Stop 6371Gaithersburg, MD 20899-6371

Darrell D. MarshallWayne State UniversityDepartment of Chemistry5101 Cass AveDetroit, MI 48202USA

Kevin G. OwensDrexel UniversityChemistry Department3141 Chestnut StreetPhiladelphia, PA 19104

Thomas PaulÖhrlKarlsruhe Institute of Technology (KIT)Institut für Technische Chemie und PolymerchemieMacromolecular ChemistryEngesserstr. 1876128 KarlsruheGermany

Concetto PuglisiNational Research Council (CNR)Institute of Chemistry and Technology of Polymers (ICTP)Via Paolo Gaifami 1895126 CataniaItaly

Yue RenWayne State UniversityDepartment of Chemistry5101 Cass AveDetroit, MI 48202USA

Alicia L. RichardsWayne State UniversityDepartment of Chemistry5101 Cass AveDetroit, MI 48202USA

Paola RizzarelliNational Research Council (CNR)Institute of Chemistry and Technology of Polymers (ICTP)Via Paolo Gaifami 1895126 CataniaItaly

Gregory T. RussellDepartment of ChemistryUniversity of Canterbury20 Kirkwood Ave.Upper Riccarton, Christchurch 8041New Zealand

Ulrich S. SchubertFriedrich-Schiller-University JenaLaboratory of Organic and Macromolecular Chemistry (IOMC)Humboldtstr. 1007743 JenaGermany

Vincenzo SciontiUniversity of AkronDepartment of Chemistry302 Buchtel CommonAkron, OH 44325USA

Sarah TrimpinWayne State UniversityDepartment of Chemistry5101 Cass AvenueDetroit, MI 48202USA

Philipp VanaGeorg-August-Universität GÖttingenInstitut für Physikalische ChemieTammannstr. 637077 GÖttingenGermany

William E. WallaceNational Institute of Standards and TechnologyChemical and Biochemical Reference Data DivisionGaithersburg, MD 20899USA

Steffen M. WeidnerBundesanstalt für Materialforschung und -prüfung (BAM)Federal Institute for Materials Research and TestingRichard-Willstätter-Strasse 1112489 BerlinGermany

Chrys WesdemiotisUniversity of AkronDepartment of Chemistry302 Buchtel CommonAkron, OH 44325USA

Introduction

Christopher Barner-Kowollik, Jana Falkenhagen, Till Gruendling, and Steffen Weidner

The first mass spectrometric experiment was arguably conducted by J. J. Thomson in the late 19th century, when he measured mass-to-charge ratios (m/z) in experiments that would eventually lead to the discovery of the electron [1]. By 1912, Thomson's investigations into the mass of charged atoms resulted in the publication of details of what could be called the first mass spectrometer [2, 3]. Interestingly, Thomson also employed one of the first man-made polymeric materials in his design of the parabola spectrograph: a material with trade name Ebonite or Vulcanite, a highly crosslinked natural rubber, which, although it was fairly brittle, provided an excellent electrical insulator and could easily be milled into shape. At the time, Thomson was most likely unaware of its chemical identity, as Staudinger's ground breaking macromolecular hypothesis was not to be established until a few years later [4]. By 1933 – the same year in which German chemist Otto Röhm patented and registered Plexiglas as a brand name – F. W. Aston had firmly established mass spectrometry as a field of analytical chemistry. Using the technique, he ascertained the isotopic abundances of essentially all of the chemical elements [5]. Thomson, Aston, and Staudinger were later to receive the Nobel Prize for their individual achievements.

Today, mass spectrometry provides the synthetic polymer chemist with one of the most powerful analytical tools to investigate the molecular structure of intact macromolecules. The development of technology that would be able to achieve this task was not realized until the late 1980s. Indeed, the mass analyzers themselves were not the key problem, as they were already fairly advanced at the time. An ionization technique that allowed the entire synthetic macromolecule to be transferred into the gas phase as ions without fragmentation could, however, only be realized in the late 1980s. The application of traditional MS ionization techniques requiring thermal evaporation of the sample to the large and entwined macromolecules was considered quite impossible, although notable attempts existed at employing the more traditional ionization techniques to polymeric material [6–8]. This perception had to undergo a drastic revision in 1988 and thereafter, the years in which electrospray ionization mass spectrometry (ESI) [9] and matrix assisted laser desorption and ionization (MALDI) [10, 11] were first reported of being capable to ionize proteins and synthetic polymers. Largely on the back of the work of four researchers, Karas [12–14], Hillenkamp [10, 12, 13], Tanaka [11], and Fenn [9, 15, 16], these new soft ionization mass spectrometry techniques commenced their success story initially in the field of biochemistry and later in synthetic polymer chemistry. Since the early 1990s, soft ionization mass spectrometry techniques have become an important part of polymer chemistry, ranging from unraveling polymerization mechanisms, assessing copolymer structures to studying the degradation of polymeric materials on a molecular level. However, a case can nevertheless be made that mass spectrometry is an underutilized tool in polymer chemistry compared to its high potential [17]. Such a notion is underpinned by an analysis of the current literature: of the approximately 10 000 studies conducted upon – for example – polyacrylates (which are readily ionizable) from 2000 until 2010, NMR spectroscopy played a significant role in 15% of these studies, whereas soft ionization mass spectrometry played a significant role in only about 3% of these studies. This is despite of the fact that soft ionization mass spectrometry technology has – due to its dominance as a highly applicable analytical tool in the biological sciences – become almost as readily available as NMR. To date, mass spectrometry remains the only technique with the power to isolate (provided the correct mass analyzer is employed) and image individual polymer chains on a routine basis.

Although there have been some notable books addressing the field of mass spectrometry applied to synthetic polymers [18–20], no publication especially dedicated to the needs of synthetic polymer chemists exists, which could aid in the selection of appropriate mass spectrometric tools. Specifically, most books on polymer mass spectrometry do not engage with the topics of living/controlled radical polymerization methods and their mechanistic underpinnings or the mass spectrometric investigation of polymerization processes in general. In addition, an up-date on the current situation of polymer mass spectrometry is required. With the present compilation, we wish to close this critical gap in the literature and provide a state-of-the-art overview on the applications of mass spectrometry in molecular polymer chemistry to the reader. In this edited publication, a series of leading researchers in the field will present their expert perspectives on several – in our view – important topics in contemporary mass spectrometry. It is thus no surprise that the large majorities of authors contributing to the present book are chemists by training, as we have attempted to provide a book that addresses the analytical requirements posed in contemporary polymer chemistry.

The book opens with an overview of the available mass analyzers. Special consideration is given by the authors Steven Blanksby and Gene Hart-Smith to their uses in polymer chemistry. Various ionization techniques applicable in polymer mass spectrometry are then explored in-depth by Anthony Gies. Chrys Wesdemiotis subsequently takes a close look at tandem mass spectrometry, a highly important tool for the elucidation of polymer structure and one of the major contemporary fields of development in the mass spectrometry sector. Sarah Trimpin and colleagues follow with their contribution, describing gas-phase ion-separation procedures as applied to synthetic polymers. The ionization process of polymers via the MALDI approach requires a careful design of the sample preparation procedures. Scott Hanton and Kevin Owens therefore provide a close look at how polymer samples are best prepared. Synthetic polymers are not only important materials in their own right, but are also frequently employed to (covalently) modify variable surfaces. Surface analysis is notoriously challenging and a range of techniques have to be employed to map the chemical characteristics of surface-bound macromolecules. Christine Mahoney and Steffen Weidner provide a detailed description of the part which surface-sensitive mass spectrometric techniques play in elucidating a polymer surface's structure.

Soft ionization mass spectrometry techniques can be especially powerful when combined with chromatographic techniques such as size exclusion chromatography (SEC), liquid adsorption chromatography at critical conditions (LACCCs) or both. Jana Falkenhagen and Steffen Weidner explore the wide variety of so-called hyphenated techniques and impressively demonstrate the information depth that can be attained by employing such technologies. While arguably the majority of molecular weight determination is carried out via SEC often equipped with refractive index as well as light scattering detectors, Till Gruendling, William Wallace, and colleagues demonstrate how MALDI-MS as well as SEC coupled to ESI-MS can be employed to deduce absolute molecular weight distributions. The chapter also provides an overview of contemporary automated data processing techniques for mass spectrometric data. Most polymers generated are arguably copolymers and it thus is mandatory to dedicate an entire chapter to the analysis of copolymers via mass spectrometry – Ulrich Schubert and Anna Crecelius provide an in-depth analysis. The field of living/controlled radical polymerization provides fascinating high precision avenues for the construction of complex macromolecular architectures and enables the generation of polymers with a high degree of end-group fidelity, which are often employed in cross-discipline applications (e.g., in biosynthetic conjugates). Soft ionization mass spectrometry plays an integral part in unraveling the mechanism of living/controlled radical polymerization processes as well as in the characterization of macromolecular building blocks: Christopher Barner-Kowollik and colleagues take a close look at the current state-of-the-art. Similarly, polymers generated via conventional radical polymerization can be readily investigated via mass spectrometry. Here, especially the investigation of the initiation process and of the generated end-group type is of high importance – Michael Buback, Greg Russell, and colleagues report. Finally, Grazyna Adamus and Marek Kowalczuk survey the field of mass spectrometry applied to polymers prepared via nonradical methods such as coordination polymerization, polycondensation, and polyaddition. The question of polymer stability and a detailed understanding of polymer degradation processes on a molecular level are of paramount importance for an evaluation of the performance of a polymer in chemical applications or as a material. Sabrina Carroccio and colleagues survey the field of soft ionization mass spectrometry applied to the molecular study of degradation processes at the book's conclusion.

With the above spectrum, we hope to have covered most of what constitutes modern mass spectrometry applied to questions of organic polymer chemistry. The final chapter provides an outlook and evaluation – from our perspective – of what the important advances in mass spectrometry technology related to polymer chemistry could be and which important chemical questions are yet to be addressed by soft ionization techniques.

Karlsruhe and Berlin, February 2011

Christopher Barner-Kowollik

Jana Falkenhagen

Till Gruendling

Steffen Weidner

References

1 Thomson, J.J. (1897) Philos. Mag., 5, 293.

2 Thomson, J.J. (1912) Philos. Mag., 24, 209.

3 Thomson, J.J. (1913) Proc. R. Soc. Lond. A, 89, 1.

4 Staudinger, H. (1920) Ber. Dtsch. Chem. Ges., 53, 1073.

5 Aston, F.W. (1933) Mass Spectra and Isotopes, Edward Arnold, London.

6 Achhammer, B.G., Reiney, M.J., Wall, L.A., and Reinhart, F.W. (1952) J. Polym. Sci., 8, 555.

7 Hummel, D.O., Düssel, H.J., and Rübenacker, K. (1971) Makromol. Chem., 145, 267.

8 Lattimer, R.P., Harmon, D.J., and Hansen, G.E. (1980) Anal. Chem., 52, 1808.

9 Meng, C.K., Mann, M., and Fenn, J.B. (1988) Z. Phys. D: At. Mol. Clusters, 10, 361.

10 Karas, M. and Hillenkamp, F. (1988) Anal. Chem., 60, 2299.

11 Tanaka, K., Waki, H., Idao, Y., Akita, S., Yoshida, Y., and Yoshida, T. (1988) Rapid Commun. Mass Spectrom., 2, 151.

12 Karas, M., Bachmann, D., Bahr, U., and Hillenkamp, F. (1987) Int. J. Mass Spectr. Ion Proc., 78, 53.

13 Karas, M., Bachmann, D., and Hillenkamp, F. (1985) Anal. Chem., 57, 2935.

14 Karas, M. and Bahr, U. (1985) Trends Anal. Chem., 5, 90.

15 Yamashita, M. and Fenn, J.B. (1984) J. Phys. Chem., 88, 4451.

16 Yamashita, M. and Fenn, J.B. (1984) J. Phys. Chem., 88, 4671.

17 Hart-Smith, G. and Barner-Kowollik, C. (2010) Macromol. Chem. Phys., 211, 1507.

18 Li, L. (2010) MALDI Mass Spectrometry for Synthetic Polymer Analysis (Chemical Analysis: A Series of Monographs on Analytical Chemistry and Its Applications), John Wiley & Sons, Hoboken, NJ.

19 Pasch, H. and Schrepp, W. (2003) MALDI-TOF Mass Spectrometry of Synthetic Polymers, Springer, Berlin.

20 Montaudo, G. and Lattimer, R.P. (2001) Mass Spectrometry of Polymers, CRC Press, Boca Raton, FL.

Chapter 1

Mass Analysis

Gene Hart-Smith and Stephen J. Blanksby

1.1 Introduction

Modern day mass analyzer technologies have, together with soft ionization techniques, opened powerful new avenues by which insights can be gained into polymer systems using mass spectrometry (MS). Recent years have seen important advances in mass analyzer design, and a suite of effective mass analysis options are currently available to the polymer chemist. In assessing the suitability of different mass analyzers toward the examination of a given polymer sample, a range of factors, ultimately driven by the scientific questions being pursued, must be taken into account. It is the aim of the current chapter to provide a reference point for making such assessments.

The chapter will open with a summary of the measures of mass analyzer performance most pertinent to polymer chemists (Section 1.2). How these measures of performance are defined and how they commonly relate to the outcomes of polymer analyses will be presented. Following this, the various mass analyzer technologies of most relevance to contemporary MS will be discussed (Section 1.3); basic operating principles will be introduced, and the measures of performance described in Section 1.2 will be summarized for each of these technologies. Finally, an instrument's tandem and multiple-stage MS (MS/MS and MSn, respectively) capabilities can play a significant role in its applicability to a given polymer system. The capabilities of different mass analyzers and hybrid mass spectrometers in relation to these different modes of analysis will be summarized in Section 1.4.

1.2 Measures of Performance

When judging the suitability of a given mass analyzer toward the investigation of a polymer system, the relevant performance characteristics will depend on the scientific motivations driving the study. In most instances, knowledge of the following measures of mass analyzer performance will allow a reliable assessment to be made: mass resolving power, mass accuracy, mass range, linear dynamic range, and abundance sensitivity. How these different performance characteristics are defined, and how they relate to the data collected from polymer samples is expanded upon in the sections below.

1.2.1 Mass Resolving Power

Mass analyzers separate gas-phase ions based on their mass-to-charge ratios (m/z); how well these separations can be performed and measured is defined by the instrument's mass resolving power. IUPAC recommendations allow for two definitions of mass resolving power [1]. The “10% valley definition” states that, for two singly charged ion signals of equal height in a mass spectrum at masses M and (M − ΔM) separated by a valley which, at its lowest point, is 10% of the height of either peak, mass resolving power is defined as M/ΔM. This definition of mass resolving power is illustrated in portion A of Figure 1.1. The “peak width definition” also defines mass resolving power as M/ΔM; in this definition, M refers to the mass of singly charged ions that make up a single peak, and ΔM refers to the width of this peak at a height which is a specified fraction of the maximum peak height. It is recommended that one of three specified fractions should always be used: 50%, 5%, or 0.5%. In practice, the value of 50% is frequently utilized; this common standard, illustrated in portion B of Figure 1.1, is termed the “full width at half maximum height” (FWHM) definition. The mass resolving power values quoted for the mass analyzers described in this chapter use the FWHM criterion.

Figure 1.1 Methods of calculating mass resolving power. Portion (A) illustrates calculation via the 10% valley definition. Portion (B) illustrates calculation via the FWHM definition.

In the context of polymer analysis, the mass resolving power is important when characterizing different analyte ions of similar but nonidentical masses. These different ions may contain separate vital pieces of information. An example of this would be if the analytes of interest contain different chain end group functionalities; characterization of these distinct end groups would allow separate insights to be gained into polymer formation processes. Whether or not this information can be extracted from the mass spectrum depends on the resolving power of the mass analyzer. The importance of mass resolving power in this context has been illustrated in using data taken from a study conducted by Szablan , who were interested in the reactivities of primary and secondary radicals derived from various photoinitiators [2]. Through the use of a 3D ion trap mass analyzer, these authors were able to identify at least 14 different polymer end group combinations within a window of 65. This allowed various different initiating radical fragments to be identified, and insights to be gained into the modes of termination that were taking place in these polymerization systems. It can be seen that the mass resolving power of the 3D ion trap allowed polymer structures differing in mass by 2 Da to be comfortably distinguished from one another.