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Author: Savannah R. Snyder
Publisher:
ISBN:
Category : Mass spectrometry
Languages : en
Pages : 146
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Book Description
The following dissertation focuses on utilizing mass spectrometry (MS) and its hyphenated techniques to understand the structure-property relationships of various stimuli-responsive polymers. By exploiting these materials' reactions to an outside stimulus, parallels can be made between the information from the mass spectral analyses and the materials' physical properties. Using techniques like tandem mass spectrometry (MS/MS), liquid chromatography (LC), and ion mobility (IM), properties of these materials were correlated to their microstructures and resultant physical functionalities. Side-chain liquid crystalline (SCLC) homopolymers and copolymers are a type of stimuli-responsive macromolecule that respond to incident light. The side-chains are generally comprised of oxygen, nitrogen, phenyl rings, etc., making their resulting structures conjugated systems. These properties allow them to polarize light. They are used in various optical applications as these mesogenic (i.e., liquid crystalline) side chains give the molecules optical anisotropy. These side-chains are what control the physical properties of these polymers and when two different types of liquid crystalline side chains are polymerized, the resultant copolymer can have vastly different properties than their respective homopolymers. Additionally, the sequence of the side-chains being random, block, alternating, or tapered also affects the physical properties. The copolymers in this study were synthesized with oxiranemethanol reacted with the mesogenic side-chains (4-cyano-4'hydroxybiphenyl, 4-[4'-pentylcyclohexyl]phenol) through a four carbon linker. Using matrix-assisted laser desorption/ionization-tandem mass spectrometry (MALDI-MS/MS) via laser-induced fragmentation (LIFT) allowed for the sequences of the designed SCLC copolymers to be identified. Particulate accumulation and deposition in the in-take valve of a vehicular engine can be the cause of many engine issues, though the cause of this buildup is not well studied. Using mass spectrometry to analyze these deposits can give insight into what they are comprised of, how they were made, and potentially, how to prevent them. Oils and fuels can mix with the air in the presence of harsh engine conditions to cause such deposits, but the formulations have components in them intended to deter this unwanted product, like detergents, dispersants, viscosity modifiers, etc. Oftentimes, these additives are low molecular weight polymers that respond to an increase in temperature, or another stimulus, aiding in the engine's cleanliness and maintenance. The more polar constituents in these blends are thought to contribute to these deposits, and also makes them more amenable to mass spectral analysis. Mass spectrometry and a variety of its hyphenated techniques (ASAP-, LC-, IM-) were used to acquire insight into the composition of these unknown samples to potentially aid in their preclusion.Finally, thermoresponsive polymers (TRPs) are stimuli-responsive polymers that alter their architecture when subjected to energy in the form of heat. They are used in biological applications for drug delivery, vehicular applications in fuels, and various other temperature-sensitive practices. The ability to change conformation in response to temperature aids in the herein studied samples' biological applications by changing hydrophobicity for sensitive biotic needs. These alterations are essentially changes to the conformation of the polymer chain itself, and generally are produced from p-NIPAM-like and methacrylate-like polymers. In order to observe this change, ion mobility-mass spectrometry (IM-MS) was used in a novel analysis to detect changes in polymer architecture when stimulated by increasing collision energy (collisional heating). The energy was then correlated to the varying pendant structures of the polymers, which showed a direct structure-property relationship between energy needed for conformational change and overall hydrophilicity/bulkiness.
Author: Savannah R. Snyder
Publisher:
ISBN:
Category : Mass spectrometry
Languages : en
Pages : 146
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Book Description
The following dissertation focuses on utilizing mass spectrometry (MS) and its hyphenated techniques to understand the structure-property relationships of various stimuli-responsive polymers. By exploiting these materials' reactions to an outside stimulus, parallels can be made between the information from the mass spectral analyses and the materials' physical properties. Using techniques like tandem mass spectrometry (MS/MS), liquid chromatography (LC), and ion mobility (IM), properties of these materials were correlated to their microstructures and resultant physical functionalities. Side-chain liquid crystalline (SCLC) homopolymers and copolymers are a type of stimuli-responsive macromolecule that respond to incident light. The side-chains are generally comprised of oxygen, nitrogen, phenyl rings, etc., making their resulting structures conjugated systems. These properties allow them to polarize light. They are used in various optical applications as these mesogenic (i.e., liquid crystalline) side chains give the molecules optical anisotropy. These side-chains are what control the physical properties of these polymers and when two different types of liquid crystalline side chains are polymerized, the resultant copolymer can have vastly different properties than their respective homopolymers. Additionally, the sequence of the side-chains being random, block, alternating, or tapered also affects the physical properties. The copolymers in this study were synthesized with oxiranemethanol reacted with the mesogenic side-chains (4-cyano-4'hydroxybiphenyl, 4-[4'-pentylcyclohexyl]phenol) through a four carbon linker. Using matrix-assisted laser desorption/ionization-tandem mass spectrometry (MALDI-MS/MS) via laser-induced fragmentation (LIFT) allowed for the sequences of the designed SCLC copolymers to be identified. Particulate accumulation and deposition in the in-take valve of a vehicular engine can be the cause of many engine issues, though the cause of this buildup is not well studied. Using mass spectrometry to analyze these deposits can give insight into what they are comprised of, how they were made, and potentially, how to prevent them. Oils and fuels can mix with the air in the presence of harsh engine conditions to cause such deposits, but the formulations have components in them intended to deter this unwanted product, like detergents, dispersants, viscosity modifiers, etc. Oftentimes, these additives are low molecular weight polymers that respond to an increase in temperature, or another stimulus, aiding in the engine's cleanliness and maintenance. The more polar constituents in these blends are thought to contribute to these deposits, and also makes them more amenable to mass spectral analysis. Mass spectrometry and a variety of its hyphenated techniques (ASAP-, LC-, IM-) were used to acquire insight into the composition of these unknown samples to potentially aid in their preclusion.Finally, thermoresponsive polymers (TRPs) are stimuli-responsive polymers that alter their architecture when subjected to energy in the form of heat. They are used in biological applications for drug delivery, vehicular applications in fuels, and various other temperature-sensitive practices. The ability to change conformation in response to temperature aids in the herein studied samples' biological applications by changing hydrophobicity for sensitive biotic needs. These alterations are essentially changes to the conformation of the polymer chain itself, and generally are produced from p-NIPAM-like and methacrylate-like polymers. In order to observe this change, ion mobility-mass spectrometry (IM-MS) was used in a novel analysis to detect changes in polymer architecture when stimulated by increasing collision energy (collisional heating). The energy was then correlated to the varying pendant structures of the polymers, which showed a direct structure-property relationship between energy needed for conformational change and overall hydrophilicity/bulkiness.
Author: Laura N. Neumann
Publisher:
ISBN:
Category :
Languages : en
Pages : 273
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Book Description
Author: Nadrah Alawani
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 238
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Book Description
This dissertation focuses on coupling mass spectrometry (MS) and tandem mass spectrometry (MS/MS) to thermal degradation, liquid chromatography (LC) and/or ion mobility (IM) spectrometry for the characterization of complex mixtures. In chapter II, an introduction of the history and the principles of mass spectrometry (MS) and liquid chromatography (LC) are discussed. Chapter III illustrates the materials and instrumentation used to complete this dissertation. Polyethers have been characterized utilizing tandem mass spectrometry (MS/MS), as presented in Chapter IV and Chapter VI. Diblock copolymers of polyethylene oxide and polycaprolactone, PEO-b-PCL, have been characterized by matrix-assisted laser desorption/ionization quadrupole/time-of-flight mass spectrometry (MALDI-Q/ToF) and LC-MS/MS (Chapter V). Thermoplastic elastomers have been characterized by thermal degradation using an atmospheric solids analysis probe (ASAP) and ion mobility mass spectrometry (IM-MS), as discussed in Chapter VII. Interfacing separation techniques with mass spectrometry permitted the detection of species present with low concentration in complex materials and improved the sensitivity of MS. In chapter IV, the fragmentation mechanisms in MS/MS experiments of cyclic and linear poly(ethylene oxide) macroinitiators are discussed. This study aimed at determining the influence of end groups on the fragmentation pathways. In the study reported in Chapter V, ultra high performance liquid chromatography (UHPLC) was interfaced with MS and MS/MS to achieve the separation and in-depth characterization and separation of amphiphilic diblock copolymers (PEO-b-PCL) in which the architecture of the PEO block is linear or cyclic. Applying UPLC-MS and UPLC-MS/MS provides fast accurate information about the number and type of the blocks in the copolymers. Chapter VI reports MS/MS and IM-MS analyses which were performed to elucidate the influence of molecular size and collision energy on the fragmentation pathways of polyethers subjected to collisionally activated dissociation (CAD). Survival yields and collision cross-sections were derived for several oligomers of polybutylene oxide (PBO) and polytetrahydrofuran (PTHF) polymers by MS/MS and IM-MS, in order to understand their fragmentation energetics and fully characterize their structures. In Chapter VII, application of atmospheric solids analysis probe (ASAP) and ion mobility (IM) separation were coupled with mass spectrometry (MS) and tandem mass spectrometry (MS/MS) to characterize commercially available thermoplastic elastomers. These compounds are mainly composed of thermoplastic copolymers, but also contain additional chemicals to enhance their properties or to protect them from degradation. Using ASAP-IM-MS enables fast analysis, involving mild degradation at atmospheric pressure (ASAP) and subsequent characterization of the desorbates and pyrolyzates by ion mobility mass spectrometry (IM-MS) and tandem mass spectrometry (MS/MS). Such multidimensional dispersion considerably simplifies the resulting spectra, permitting the conclusive separation and characterization of the multicomponent materials examined. Chapter VIII summarizes the findings of this dissertation and is followed by appendices with supplemental data and the copyright permissions obtained for this dissertation.
Author: Aleer Manyuon Yol
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 104
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Book Description
The matrix-assisted laser desorption ionization time-of-flight/time-of-flight mass spectrometry (MALDI-ToF/ToF MS) characteristics of different polystyrenes and polybutadienes are discussed in this dissertation. The compounds examined include linear, cyclic, in-chain substituted, and star-branched polymers as well as copolymers of styrene and either para-dimethylsilyl styrene (p-DMSS) or meta-dimethylsilyl styrene (m-DMSS). Chapter IV describes the differentiation of cyclic and linear polymers by 2D-mass spectrometry. The silverated quasimolecular ions from cyclic and linear polystyrenes and polybutadienes, formed by MALDI, give rise to significantly different fragmentation patterns in tandem mass spectrometry (MS2) experiments. With both architectures, fragmentation starts with homolytic cleavage at the weakest bond, usually a C-C bond, to generate two radicals. From linear structures, the separated radicals depolymerize extensively by monomer losses and backbiting rearrangements, leading to low-mass radical ions and much less abundant medium- and high-mass closed-shell fragments that contain one of the original end groups, along with internal fragments. With cyclic structures, depolymerization is less efficient, as it can readily be terminated by intramolecular H-atom transfer between the still interconnected radical sites (disproportionation). These differences in fragmentation reactivity result in substantially different fragment ion distributions in the MS2 spectra. Simple inspection of the relative intensities of low- vs. high-mass fragments permits conclusive determination of the macromolecular architecture, while full spectral interpretation reveals the individual end groups of the linear polymers or the identity of the linker used to form the cyclic polymer. Chapter V presents the first sequence analysis of styrenic copolymers by tandem MS. Copolymers of para-dimethylsilyl styrene (p-DMSS) or m-DMSS with styrene were prepared by living anionic polymerization. The MALDI-MS2 results for p-DMSS indicate that a block copolymer is formed, with the para-substituted styrene incorporated near the initiator. On the other hand, the MS2 results of m-DMSS reveal that a random copolymer is formed, consistent with comparable reactivities for m-DMSS and styrene. These findings suggest that p-DMSS is more reactive than m-DMSS. The single-stage (1D) MALDI-MS results further show that linear and 2-armed architectures are formed with both the m-DMSS and the p-DMSS comonomers. The last Chapter, VI, focuses on the differentiation of linear in-chain substituted, cyclic, and star-branched polystyrene (PS) by tandem mass spectrometry. The in-chain functionalized PS gives a MS2 fragmentation pattern that is different from the one observed for cyclic PS with two linker units and, again, with a simple inspection of the tandem mass spectra, these architectures can easily be distinguished. The four-arm star-branched polymer investigated mainly breaks down by losing arms under MALDI-MS2 conditions. Overall, this dissertation documents the usefulness of combined 1D and 2D mass spectrometry experiments for the identification of polymer substituents and their location, for distinguishing polymer architectures, and for determining copolymer sequences.The results presented in this dissertation have been published or are pending for publication in the following journals. 1. Quirk, R. P.; Wang, S-F.; Foster, M. D.; Wesdemiotis, C.; Yol, A. M. "Synthesis of Cyclic Polystyrenes Using Living Anionic Polymerization and Metathesis Ring-Closure" Macromolecules 2011, 44, 7538-7545. 2. Liu, B.; Quirk, R. P.; Wesdemiotis, C.; Yol, A. M.; Foster, M. D. "Precision Synthesis of [omega]-Branch, End-Functionalized Comb Polystyrenes Using Living Anionic Polymerization and Thiol-Ene 'Click' Chemistry" Macromolecules 2012, 45, 9233-9242. 3. Yol, A. M.; Dabney, D. E.; Wang, S-F.; Laurent, B. A.; Foster, M. D.; Quirk, R. P.; Grayson, S. M.; Wesdemiotis, C. "Differentiation of Linear and Cyclic Polymer Architectures by MALDI Tandem Mass Spectrometry (MALDI-MS2)" J. Am. Soc. Mass Spectrom. 2013, 24, 74-82. 4. Quirk, R.P.; Chavan, V.; Janoski, J.; Yol, A.; Wesdemiotis, C. "General Functionalization Method for Synthesis of [alpha]-Functionalized Polymers by Combination of Anionic Polymerization and Hydrosilation Chemistry" Macromolecular Symposia 2013, 323, 51-57. 5. Yol, A. M.; Janoski, J.; Quirk, R. P.; Wesdemiotis, C. "Sequence Analysis of Styrenic Copolymers by Tandem Mass Spectrometry" Anal. Chem. (Submitted)
Author: Andrea Cusano
Publisher: Springer
ISBN: 3319069985
Category : Science
Languages : en
Pages : 377
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Book Description
This book focuses on a research field that is rapidly emerging as one of the most promising ones for the global optics and photonics community: the “lab-on-fiber” technology. Inspired by the well-established "lab on-a-chip" concept, this new technology essentially envisages novel and highly functionalized devices completely integrated into a single optical fiber for both communication and sensing applications. Based on the R&D experience of some of the world's leading authorities in the fields of optics, photonics, nanotechnology, and material science, this book provides a broad and accurate description of the main developments and achievements in the lab-on-fiber technology roadmap, also highlighting the new perspectives and challenges to be faced. This book is essential for scientists interested in the cutting-edge fiber optic technology, but also for graduate students.
Author: Pietro Matricardi
Publisher: CRC Press
ISBN: 9814613622
Category : Medical
Languages : en
Pages : 527
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Book Description
Hydrogels are an emerging area of interest in medicine as well as pharmaceutics, and their physico-chemical characterization is fundamental to their practical applications. Compared with synthetic polymers, polysaccharides that are widely present in living organisms and come from renewable sources are extremely advantageous for hydrogel formation.
Author: Jinlian Hu
Publisher: Smithers Rapra
ISBN: 1909030333
Category : Science
Languages : en
Pages : 326
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Book Description
Shape-memory polymers (SMP) are a unique branch of the smart materials family which are capable of changing shape on-demand upon exposure to external stimulus. The discovery of SMP made a significant breakthrough in the developments of novel smart materials for a variety of engineering applications, superseded the traditional materials, and also influenced the current methods of product designing. This book provides the latest advanced information of on-going research domains of SMP. This will certainly enlighten the reader to the achievements and tremendous potentials of SMP. The basic fundamentals of SMP, including shape-memory mechanisms and mechanics are described. This will aid reader to become more familiar with SMP and the basic concepts, thus guiding them in undergoing independent research in the SMP field. The book also provides the reader with associated challenges and existing application problems of SMP. This could assist the reader to focus more on these issues and further exploit their knowledge to look for innovative solutions. Future outlooks of SMP research are discussed as well. This book should prove to be extremely useful for academics, R&D managers, researcher scientists, engineers, and all others related to the SMP research.
Author: Maria Rosa Aguilar
Publisher: Elsevier
ISBN: 0857097024
Category : Technology & Engineering
Languages : en
Pages : 587
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Book Description
Smart polymers are polymers that respond to different stimuli or changes in the environment. Smart Polymers and their Applications reviews the types, synthesis, properties, and applications of smart polymers. Chapters in part one focus on types of polymers, including temperature-, pH-, photo-, and enzyme-responsive polymers. Shape memory polymers, smart polymer hydrogels, and self-healing polymer systems are also explored. Part two highlights applications of smart polymers, including smart instructive polymer substrates for tissue engineering; smart polymer nanocarriers for drug delivery; the use of smart polymers in medical devices for minimally invasive surgery, diagnosis, and other applications; and smart polymers for bioseparation and other biotechnology applications. Further chapters discuss the use of smart polymers for textile and packaging applications, and for optical data storage. Smart Polymers and their Applications is a technical resource for chemists, chemical engineers, mechanical engineers, and other professionals in the polymer industry; manufacturers in such sectors as medical, automotive, and aerospace engineering; and academic researchers in polymer science. Reviews the different types of smart polymer, discussing their properties, structure, design, and characterization Reviews applications of smart polymers in such areas as biomedical engineering, textiles, and food packaging
Author: Stuart R. Batten
Publisher: Royal Society of Chemistry
ISBN: 0854048375
Category : Science
Languages : en
Pages : 440
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Book Description
The field of coordination polymer research is now vast, & one of the fastest growing areas of chemistry in recent times, with important work being done on a variety of different aspects. This book provides a broad overview of all the major facets of modern coordination polymer science in the one place.
Author: Dirk Kuckling
Publisher: MDPI
ISBN: 303897210X
Category : Science
Languages : en
Pages : 289
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Book Description
This book is a printed edition of the Special Issue "Stimuli-Responsive Gels" that was published in Gels
