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Wesdemiotis C, Williams-Pavlantos KN, Keating AR, McGee AS, Bochenek C. Mass spectrometry of polymers: A tutorial review. MASS SPECTROMETRY REVIEWS 2024; 43:427-476. [PMID: 37070280 DOI: 10.1002/mas.21844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 03/03/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Ever since the inception of synthetic polymeric materials in the late 19th century, the number of studies on polymers as well as the complexity of their structures have only increased. The development and commercialization of new polymers with properties fine-tuned for specific technological, environmental, consumer, or biomedical applications requires powerful analytical techniques that permit the in-depth characterization of these materials. One such method with the ability to provide chemical composition and structure information with high sensitivity, selectivity, specificity, and speed is mass spectrometry (MS). This tutorial review presents and exemplifies the various MS techniques available for the elucidation of specific structural features in a synthetic polymer, including compositional complexity, primary structure, architecture, topology, and surface properties. Key to every MS analysis is sample conversion to gas-phase ions. This review describes the fundamentals of the most suitable ionization methods for synthetic materials and provides relevant sample preparation protocols. Most importantly, structural characterizations via one-step as well as hyphenated or multidimensional approaches are introduced and demonstrated with specific applications, including surface sensitive and imaging techniques. The aim of this tutorial review is to illustrate the capabilities of MS for the characterization of large, complex polymers and emphasize its potential as a powerful compositional and structural elucidation tool in polymer chemistry.
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Affiliation(s)
| | | | - Addie R Keating
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Andrew S McGee
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Calum Bochenek
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
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Song W, Campen S, Shiel H, Gattinoni C, Zhang J, Wong JSS. Position of Carbonyl Group Affects Tribological Performance of Ester Friction Modifiers. ACS APPLIED MATERIALS & INTERFACES 2024; 16:14252-14262. [PMID: 38456401 PMCID: PMC10958443 DOI: 10.1021/acsami.3c16432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/16/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024]
Abstract
The tribological properties of lubricants can be effectively improved by the introduction of amphiphilic molecules, whose performance is largely affected by their polar head groups. In this work, the tribological performance in steel-steel contacts of two isomers, glycerol monostearate (GMS) and stearyl glycerate (SG), a glyceride and a glycerate, were investigated as organic friction modifiers (OFM) in hexadecane. SG exhibits a much lower friction coefficient and wear than GMS despite their similar structures. The same applies when comparing the performance of oleyl glycerate (OG) and its isomer, glycerol monooleate (GMO). Surface chemical analysis shows that SG forms a polar, carbon-based, tribofilm of around tens of nanometers thick, while GMS does not. This tribofilm shows low friction and robustness under nanotribology test, which may contribute to its superior performance at the macro-scale. The reason for this tribofilm formation can be due to the stronger adsorption of SG on the steel surface than that of GMS. The tribofilm formation can be stress-activated since lower friction and higher tribofilm coverage can be obtained under high load. This work offers insights into the lubrication mechanism of a novel OFM and provides strategies for OFM design.
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Affiliation(s)
- Wei Song
- The
Tribology Group, Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
| | - Sophie Campen
- The
Tribology Group, Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
| | - Huw Shiel
- Department
of Material, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
| | - Chiara Gattinoni
- Department
of Physics, King’s College London, Strand, London WC2R 2LS, U.K.
| | - Jie Zhang
- The
Tribology Group, Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
| | - Janet S. S. Wong
- The
Tribology Group, Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
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Bamford SE, Yalcin D, Gardner W, Winkler DA, Kohl TM, Muir BW, Howard S, Bruton EA, Pigram PJ. Multi-Dimensional Machine Learning Analysis of Polyaniline Films Using Stitched Hyperspectral ToF-SIMS Data. Anal Chem 2023; 95:7968-7976. [PMID: 37172328 DOI: 10.1021/acs.analchem.3c00769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The self-organizing map with relational perspective mapping (SOM-RPM) is an unsupervised machine learning method that can be used to visualize and interpret high-dimensional hyperspectral data. We have previously used SOM-RPM for the analysis of time-of-flight secondary ion mass spectrometry (ToF-SIMS) hyperspectral images and three-dimensional (3D) depth profiles. This provides insightful visualization of features and trends of 3D depth profile data, using a slice-by-slice view, which can be useful for highlighting structural flaws including molecular characteristics and transport of contaminants to a buried interface and characterization of spectra. Here, we apply SOM-RPM to stitched ToF-SIMS data sets, whereby the stitched data are used to train the same model to provide a direct comparison in both 2D and 3D. We conduct an analysis of spin-coated polyaniline (PANI) films on indium tin oxide-coated glass slides that were subjected to heat treatment under atmospheric conditions to model PANI as a conformal aerospace industry coating. Replicates were shown to be precisely equivalent, both spatially and by composition, indicating a clear threshold for annealing of the film. Quantitative assessment was performed on the chemical breakdown trends accompanying annealing based on peak ratios, while spectral analysis alone shows only very subtle differences which are difficult to evaluate quantitatively. The SOM-RPM method considers data sets in their totality and highlights subtle differences between samples often simply differences in peak intensity ratios.
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Affiliation(s)
- Sarah E Bamford
- Centre for Materials and Surface Science and Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Dilek Yalcin
- Centre for Materials and Surface Science and Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
- CSIRO Manufacturing, Clayton, Victoria 3168, Australia
| | - Wil Gardner
- Centre for Materials and Surface Science and Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
| | - David A Winkler
- La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria 3086, Australia
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Thomas M Kohl
- CSIRO Manufacturing, Clayton, Victoria 3168, Australia
| | | | - Shaun Howard
- CSIRO Manufacturing, Clayton, Victoria 3168, Australia
| | - Eric A Bruton
- Boeing Defense, Space and Security, P.O. Box 516, St. Louis, Missouri 63166, United States
| | - Paul J Pigram
- Centre for Materials and Surface Science and Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
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Near ambient N2 fixation on solid electrodes versus enzymes and homogeneous catalysts. Nat Rev Chem 2023; 7:184-201. [PMID: 37117902 DOI: 10.1038/s41570-023-00462-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/31/2022] [Indexed: 02/04/2023]
Abstract
The Mo/Fe nitrogenase enzyme is unique in its ability to efficiently reduce dinitrogen to ammonia at atmospheric pressures and room temperature. Should an artificial electrolytic device achieve the same feat, it would revolutionize fertilizer production and even provide an energy-dense, truly carbon-free fuel. This Review provides a coherent comparison of recent progress made in dinitrogen fixation on solid electrodes, homogeneous catalysts and nitrogenases. Specific emphasis is placed on systems for which there is unequivocal evidence that dinitrogen reduction has taken place. By establishing the cross-cutting themes and synergies between these systems, we identify viable avenues for future research.
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Kim KH, Nam J, Choi J, Seo M, Bang J. From macromonomers to bottlebrush copolymers with sequence control: synthesis, properties, and applications. Polym Chem 2022. [DOI: 10.1039/d2py00126h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bottlebrush polymers (BBPs) are a type of comb-like macromolecules with densely grafted polymeric sidechains attached to the polymer backbones, and many intriguing properties and applications have been demonstrated due to...
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