Preparation of Perfluorinated Ionomers for Fuel Cell Applications
Preparation of Perfluorinated Ionomers for Fuel Cell Applications

Author: Todd Stephen Sayler

Publisher:

Published: 2012

Total Pages: 248

ISBN-13:

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One of the major issues with the current membrane technology for polymer electrolyte membrane fuel cells is the low conductivity seen at low relative humidity. This dissertation discloses the preparation of perfluorinated polymers with higher densities of acid sites and higher conductivities to overcome this issue. These materials are prepared using a system designed to safely synthesize and polymerize tetrafluoroethylene (TFE) on a hundred gram scale. The copolymerization of TFE and perfluoro-2-(2-fluorosulfonylethoxy) propyl vinyl ether (PSEPVE) to prepare materials with varying ratios of the two monomers was carried out by solution, bulk, and emulsion polymerization techniques. Additionally, the homopolymer of PSEPVE has been prepared and characterized by MALDI-TOF mass spectrometry, which shows the low molecular weight distribution seen in other similar materials in the literature is due to a high rate of [beta]-scission termination. Spectroscopic measurements and thermal analysis were carried out on these samples to obtain better characterization than was currently available. Producing polymers with a higher amount of PSEPVE, and thus higher density of acid sites, leads to the materials becoming water soluble after hydrolysis. However, addition of a curable ter-monomer allows the polymer chains to be crosslinked to regain water insolubility. Using this approach, water insoluble membranes with high densities of acid sites and conductivities up to 5.5 times higher than Nafion® 115, the standard benchmark for fuel cell membranes, have been produced. Preparation of high molecular weight, low EW copolymers of TFE and PSEPVE is difficult due to the reactivity ratios of the two monomers. Literature reactivity ratios for VDF and PSEPVE are more favorable for preparation of high molecular weight, low EW copolymers. Here, alternating copolymers of VDF and PSEPVE are prepared for the first time; where high molecular weight samples have been shown to possess low swelling characteristics in water. It has also been found the lower molecular weight samples that are soluble in perfluorohexane can be converted to perfluorinated polymers by direct fluorination with 20% elemental fluorine in nitrogen with 254 nm UV irradiation.

Fluorinated Ionomers
Fluorinated Ionomers

Author: Walther Grot

Publisher: William Andrew

Published: 2011-07-15

Total Pages: 313

ISBN-13: 1437744583

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Fluorinated ionomer polymers form impermeable membranes that conduct electricity, properties that have been put to use in large-scale electrochemical applications, revolutionizing the chlor-alkali industry and transforming production methods of some of the world’s highest-production commodity chemicals: chlorine, sodium hydroxide and potassium hydroxide. The use of fluorinated ionomers such as Nafion® have removed the need for mercury and asbestos in these processes and led to a massive reduction in electricity usage in these highly energy-intensive processes. Polymers in this group have also found uses in fuel-cells, metal-ion recovery, water electrolysis, plating, surface treatment of metals, batteries, sensors, drug release technologies, gas drying and humidification, and super-acid catalysis used in the production of specialty chemicals. Walther Grot, who invented Nafion® while working for DuPont, has written this book as a practical guide to engineers and scientists working in electrochemistry, the fuel cell industry and other areas of application. His book is a unique guide to this important polymer group and its applications, in membranes and other forms. The 2e expands this handbook by over a third, with new sections covering developments in electrolysis and membranes, additional information about the synthesis and science of the polymer group, and an enhanced provision of reference data. An essential reference for scientists working with electrolysis and electrochemical processes (the use of this polymer group in industrial chemistry processes is credited with a 1% reduction in global electricity usage) Covers the techniques involved in the growing range of applications for fluorinated ionomers, including fuel cells, batteries and drug delivery The only book on this important polymer group, written by Walther Grot, the inventor of the leading fluorinated ionomer, Nafion® from DuPont

Step-growth Polymerization of Perfluoro-vinyl Ether, -cycloalkenes, and -acyclic Alkenes with Bisphenols Containing Variable Polycyclic Aromatic Cores
Step-growth Polymerization of Perfluoro-vinyl Ether, -cycloalkenes, and -acyclic Alkenes with Bisphenols Containing Variable Polycyclic Aromatic Cores

Author: Karl Mpumbwa Mukeba

Publisher:

Published: 2022

Total Pages: 0

ISBN-13:

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This dissertation reports the synthesis and characterization of semi-fluorinated polymers derived from the polymerization of bisphenols with fluoroalkenes. A series of diverse bisphenols were chosen from popular commercial bisphenols and new polycyclic aromatic hydrocarbon (PAH) derived bisphenols requiring synthesis. Step-growth condensation polymerization of bisphenols with three different fluoroalkene types was performed while probing polymerization conditions and the structure/properties relationship of the resulting fluoropolymers. The fluoroalkene monomers were chosen from bis(trifluorovinyloxy)biphenyl (TFVE), perfluorocyclohexene (PFCH), and perfluoro acyclic monomers, namely, perfluoro(4-methyl-2-pentene) and 1-perfluoroheptene to undergo this chemistry. This work is divided into four parts based on the polymerization methodology. The first section focuses on the development of a new class of fluorinated arylene vinylene ether (FAVE) and their chain extended polymers prepared via base-catalyzed step-growth polymerization of PAH bisphenols with the TFVE monomer. These reactions afforded polymers containing controlled terminal and enchained fluoroalkenylenes for latent reactivity such as post polymerization functionalization, chain extension, and/or crosslinking. In general, these PAH cores resulted in polymers with improved thermal properties. The second portion describes the investigation of step-growth addition/elimination polymerizations of PAH bisphenols and PFCH to prepare a new class of fluoropolymers containing alternating rigid PAH linkages and enchained PFCH vinylene ether moieties in the backbone. The third section covers the preparation and characterization of semi-fluorinated poly(aryl ether sulfone)s by nucleophilic addition/elimination reactions of PFCH with sulfone bisphenols. From commercially bisphenols combined with PAH bisphenols, we introduced the industrially valuable and property enhancing diaryl sulfone unit in a series of semi-fluorinated copolymers. This modular approach greatly expands access to partially fluorinated aryl ether sulfone polymers intended for high performance applications in optoelectronics, separation/purification membranes, and composites. Finally, in the fourth section, a new class of semifluorinated polymers was synthesized via nucleophilic addition/elimination reactions of acyclic perfluoroalkenes with bisphenols. In particular, environmental concerns for biopersistent and highly regulated perfluorooctanoic acid (PFOA) is the driver for using perfluoroheptene, which is derived cleanly by the decarboxylation of these pollutants in one step. This provided a new class of semi-fluorinated materials with promising properties including thermal stable, processability, and transparent film formation.

Introduction to Fluoropolymers
Introduction to Fluoropolymers

Author: Sina Ebnesajjad

Publisher: William Andrew

Published: 2013-05-11

Total Pages: 345

ISBN-13: 1455775517

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Introduction to Fluoropolymers demystifies fluoropolymers for a wide audience of designers, engineers, sales staff and managers. This important group of high-performance polymers has applications across a wide range of market sectors, including automotive, aerospace, medical devices, high performance apparel, oil & gas, renewable energy / solar photovoltaics, electronics / semiconductor, pharmaceuticals, and chemical processing. Dr. Ebnesajjad covers the history and applications of a wide variety of materials, including expanded polytetrafluoroethylene, polyvinyl fluoride, vinylidene fluoride polymers and fluoroelastomers, just to name a few. Properties and applications are illustrated by real-world examples as diverse as waterproof clothing, vascular grafts and coatings for aircraft interiors. The different applications of fluoropolymers show the benefits of a group of materials that are highly water-repellant and flame-retardant, with unrivalled lubrication properties and a high level of biocompatibility. Health and safety and environmental aspects are also covered throughout the book. Demystifies fluoropolymers for a broad audience of engineers in areas such as product design and manufacturing, as well as for non-engineers such as technical sales and management professionals Explains the potential of fluoropolymers for a wide range of applications across sectors such as aerospace, energy and medical devices Ideal for both recently qualified engineers and engineers with limited experience of fluoropolymers

Polymeric Reagents and Catalysts
Polymeric Reagents and Catalysts

Author: Warren T. Ford

Publisher:

Published: 1986

Total Pages: 312

ISBN-13:

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Examines recent advances in the use of polymeric reagents and catalysts with a special emphasis on new compounds, synthetic methods, and industrial processes. Brings these advances to the attention of those who are involved in organic synthesis and desire a more thorough understanding of polymers and polymeric reagents. Contains comprehensive chapters devoted to polymeric oxidizing agents, Wittig reagents, and synthesis of cross-linked polymeric templates for chiral recognition. Presents opportunities for invention and use of many new polymeric reagents and catalysts.

The cost of inaction
The cost of inaction

Author: Gretta Goldenman

Publisher: Nordic Council of Ministers

Published: 2019-03-17

Total Pages: 194

ISBN-13: 9289360658

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PFAS (per and polyfluoroalkylsubstances) are known to be extremely difficult to degrade in the environment and to be bioaccumulative and toxic. Exposure to PFAS is suspected to increase the risk of adverse health effects, such as impacts on the thyroid gland, the liver, fat metabolism and the immune system. This study estimates the socioeconomic costs that may result from impacts on human health and the environment from the use of PFAS. Better awareness of the costs and problems associated with PFAS exposure will assist decision-makers and the general public to make more efficient and timely risk management decisions. Findings indicate that the costs are substantial, with annual health-related costs estimated to 2.8 – 4.6 billion EUR for the Nordic countries and 52 – 84 billion EUR for all EEA countries. Overall non-health costs are estimated at 46 million – 11 billion EUR for the Nordic countries.Upon request the excel spreadsheets used for the monetarisation and valuation in this report can also be provided along with a guidance on how to use the estimation of costs for value transfer. Please contact any of the consultants or members of the steering group from the Swedish Chemicals Agency or the Danish Environmental Protection Agency if you are interested in receiving these excel spreadsheets.

Acidity and Basicity of Solids
Acidity and Basicity of Solids

Author: J. Fraissard

Publisher: Springer

Published: 2012-10-25

Total Pages: 513

ISBN-13: 9789401044271

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The subject of acidity and basicity has enormous economic and technological value while it continues to present significant scientific challenges with prospects for further important technological developments. Historically, technological developments in acidity/basicity have often preceded the scientific understanding of the phenomena involved, certainly in the petroleum industry, a key beneficiarry and user of the concepts of acidity. This process, however, is very expensive and less efficient than developments based on a fundamental understanding of the scientific phenomena involved. This has been recognized over the years and it explains why university, government and industrial laboratories have in the last 50 years devoted large efforts to understanding acidity (and basicity to a lesser extent) so they can gain the technological advantage. The scientific and technological literature on the subject is truly enormous. There have been some very important articles and books on the subject that have attempted to critically review many individual contributions. During the last few years there have been three developments that led us to organize the Advanced Study Institute on which this volume is based: a) Significant developments in the theory of acids and bases; b) Developments in instrumentation that allow the detailed characterization of materials including in-situ conditions relevant to industrial processes; c) The realization that closer coupling of scientific and technological pursuits can lead to greater scientific understanding and better technology. The structure of the ASI reflected the coming-together of these three factors.

Microelectronics Processing
Microelectronics Processing

Author: L. A. Casper

Publisher:

Published: 1986

Total Pages: 464

ISBN-13:

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Examines leading-edge developments in the field of materials development. Covers all major aspects of materials science, with applications to many high technology areas. Explores the role of chemistry in high-tech materials and their applications.