Fluorinated Polymers: Applications (2) - Rilegato

Rilegato

ISBN 10: 1782629165 ISBN 13: 9781782629160

Casa editrice: Royal Society of Chemistry, 2016

Riassunto

Fluoropolymers display a wide range of remarkable properties and are used in a number of applications including high performance elastomers, thermoplastics, coatings for optical fibers, and hydrophobic and lipophobic surfaces.

Fluorinated Polymers: Applications covers the recent developments in the uses of fluoropolymers. Examples include materials for energy applications such as fuel cell membranes, lithium ion batteries and photovoltaics, as well as high-tech areas such as aerospace and aeronautics, automotives, building industries, textile finishings and electronics.

Written by internationally recognized academic and industrial contributors, the book will be of interest to those in industry and academia working in the fields of materials science, polymer chemistry and energy applications of polymers.

Together with Fluorinated Polymers: Synthesis, Properties, Processing and Simulation, these books provide a complete overview of different fluorinated polymer materials and their uses.

Su questo libro

Dalla quarta di copertina

Fluoropolymers display a wide range of remarkable properties and are used in a number of applications including high performance elastomers, thermoplastics, coatings for optical fibers, and hydrophobic and lipophobic surfaces.

Fluorinated Polymers: Applications covers the recent developments in the uses of fluoropolymers. Examples include materials for energy applications such as fuel cell membranes, lithium ion batteries and photovoltaics, as well as high-tech areas such as aerospace and aeronautics, automotives, building industries, textile finishings and electronics.

Written by internationally recognized academic and industrial contributors, the book will be of interest to those in industry and academia working in the fields of materials science, polymer chemistry and energy applications of polymers.

Together with Fluorinated Polymers: Synthesis, Properties, Processing and Simulation, these books provide a complete overview of different fluorinated polymer materials and their uses.

Dal risvolto di copertina interno

Fluoropolymers display a wide range of remarkable properties and are used in a number of applications including high performance elastomers, thermoplastics, coatings for optical fibers, and hydrophobic and lipophobic surfaces.

Fluorinated Polymers: Applications covers the recent developments in the uses of fluoropolymers. Examples include materials for energy applications such as fuel cell membranes, lithium ion batteries and photovoltaics, as well as high-tech areas such as aerospace and aeronautics, automotives, building industries, textile finishings and electronics.

Written by internationally recognized academic and industrial contributors, the book will be of interest to those in industry and academia working in the fields of materials science, polymer chemistry and energy applications of polymers.

Together with Fluorinated Polymers: Synthesis, Properties, Processing and Simulation, these books provide a complete overview of different fluorinated polymer materials and their uses.

Estratto. © Ristampato con autorizzazione. Tutti i diritti riservati.

Fluorinated Polymers Volume 2: Applications

By Bruno Ameduri, Hideo Sawada

The Royal Society of Chemistry

Copyright © 2017 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-78262-916-0

Contents

Volume 1, 
SYNTHESIS, 
Chapter 1 Fluorinated Peroxides as Initiators of Fluorinated Polymers Shohei Yamazaki and Hideo Sawada, 3, 
Chapter 2 Fluoroalkylated Styrene Dimers: Synthesis, Properties, and Applications Masato Yoshida, 22, 
Chapter 3 Anionic Polymerization of Fluorinated Vinyl Monomers Tadashi Narita, 40, 
Chapter 4 Polyaddition of Fluorinated Vinyl Monomers Tadashi Narita, 72, 
Chapter 5 Semifluorinated Aromatic Polymers and Their Properties Susanta Banerjee and Anindita Ghosh, 103, 
Chapter 6 Synthesis of Fluoro-functional Conjugated Polymers by Electrochemical Methods Shinsuke Inagi, 190, 
Chapter 7 Supercritical Carbon Dioxide as Reaction Medium for Fluoropolymer Synthesis and Kinetic Investigations into Radical Polymerizations of VDF and HFP Benjamin Hosemann, Rebekka Siegmann and Sabine Beuermann, 211, 
PROPERTIES, 
Chapter 8 Structure-Property Relations in Semifluorinated Polymethacrylates D. Pospiech, D. Jehnichen, P. Chunsod, P. Friedel, F. Simon and K. Grundke, 235, 
Chapter 9 Preparation and Self-assembly of Amphiphilic Fluoropolymers Chun Feng and Xiaoyu Huang, 276, 
PROCESSING, 
Chapter 10 The Melt Viscosity Properties of Fluoroplastics - Correlations to Molecular Structure and Tailoring Principles Harald Kaspar, 309, 
SIMULATION, 
Chapter 11 Molecular Simulation of Fluorinated Telomer and Polymers, 361, 
Subject Index, 386, 
Volume 2, 
APPLICATIONS, 
Chapter 1 Industrial Aspects of Fluorinated Oligomers and Polymers Rudy Dams and Klaus Hintzer, 3, 
Chapter 2 Fluoroalkyl Acrylate Polymers and Their Applications Ikuo Yamamoto, 32, 
Chapter 3 Structural Diversity in Fluorinated Polyphosphazenes: Exploring the Change from Crystalline Thermoplastics to High-performance Elastomers and Other New Materials Harry R. Allcock, 54, 
Chapter 4 Fluoroplastics and Fluoroelastomers - Basic Chemistry and High-performance Applications Masahiro Ohkura and Yoshitomi Morizawa, 80, 
Chapter 5 Fluorinated Specialty Chemicals - Fluorinated Copolymers for Paints and Perfluoropolyethers for Coatings Taiki Hoshino and Yoshitomi Morizawa, 110, 
Chapter 6 Commercial Synthesis and Applications of Poly(Vinylidene Fluoride) James T. Goldbach, Ramin Amin-Sanayei, Wensheng He, James Henry, Walt Kosar, Amy Lefebvre, Gregory O'Brien, Diane Vaessen, Kurt Wood and Saeid Zerafati, 127, 
Chapter 7 The Role of Perfluoropolyethers in the Development of Polymeric Proton Exchange Membrane Fuel Cells M. Sansotera, M. Gola, G. Dotelli and W. Navarrini, 158, 
Chapter 8 Fluorinated Ionomers and Ionomer Membranes: Monomer and Polymer Synthesis and Applications Takeshi Hirai and Yoshitomi Morizawa, 179, 
Chapter 9 Research and Non-major Commercial Co- and Terpolymers of Tetrafluoroethylene Daniel A. Hercules, Cameron A. Parrish and Joseph S. Thrasher, 206, 
Chapter 10 Chlorotrifluoroethylene Copolymers for Energy-applied Materials Bruno Ameduri, 265, 
Chapter 11 Fabrication of Flexible Transparent Nanohybrids with Heat-resistance Properties Using a Fluorinated Crystalline Polymer Atsuhiro Fujimori, 301, 
Chapter 12 Creation of Superamphiphobic, Superhydrophobic/Superoleophilic and Superhydrophilic/Superoleophobic Surfaces by Using Fluoroalkyl-endcapped Vinyltrimethoxysilane Oligomer as a Key Intermediate Hideo Sawada, 353, 
Subject Index, 366, 

CHAPTER 1

Industrial Aspects of Fluorinated Oligomers and Polymers

RUDY DAMS AND KLAUS HINTZER

1.1 Introduction

In the early 1930s, researchers of IG-Farbenindustrie in Frankfurt (Germany) studied systematically the first polymerizations of fluoroethenes; the Hoechst researchers had already prepared polychlorotrifluoroethylene (PCTFE) and polytetrafluoroethylene (PTFE), including copolymers, recognizing the outstanding properties of these polymers. The first patent application for a fluoropolymer was filed in October 1934 by Schloffer and Scherer. PTFE was also discovered in 1938 in the USA by Plunkett of E. I. DuPont de Nemours while investigating fluorinated refrigerants. The unique properties of PTFE were recognized during the Manhattan Project, where there was an urgent need for a material that would withstand the highly corrosive environment during the process of separating the isotopes of UF for the first atomic bomb. PTFE apparently fulfilled all the needs, spurring the development of processing and production methods for this unique polymer. In 1946, PTFE was commercialized by E. I. DuPont de Nemours under the trade name Teflon.

The unique properties of fluoropolymers are due to the fact that the polymer backbone is formed by strong carbon-carbon bonds (C-C ~ 340 kJ mol-1) and extremely stable carbon-fluorine bonds (C-F ~490 kJ mol-1; for comparison, C-H ~420 kJ mol-1). Substitution of fluorine for hydrogen in a material improves three key physical properties:

• increased service temperatures and reduced flammability;

• low surface energy, providing non-stick properties/anti-adhesiveness, low coefficient of friction, self-lubricating effects and lower solubility in hydrocarbons;

• excellent electrical and optical properties resulting in low high-frequency-loss rates and low refractive indices.

PTFE, PCTFE and all other fluoropolymers (see Table 1.2) gained immediate acceptance during commercialization in the various markets.

During the following decades, many fluoropolymers, including fluorothermoplastics and fluoroelastomers, were developed. The worldwide annual sales volume of fluoropolymers is today more than 230 000 tonnes (world consumption of fluoroplastics in 2012 was ~ 216 000 tonnes; world consumption of fluoroelastomers in 2009 was ~ 20 000 tonnes). The total market value is more than US$6 billion.

In contrast to the higher molecular weight polymers, oligomers are characterized by a low number of repeating units, usually less than 50, and a low molecular weight, often not higher than 20 000 Da (as measured by gel permeation chromatography).

Many synthetic routes to oligomers have been described, including radical oligomerization, oligocondensation, ionic oligomerization and ring-opening reactions. Telomerization is an oligomerization by a chain-transfer reaction, carried out in the presence of a large amount of chain-transfer agent, so that end-groups are essentially fragments of the chain-transfer agent. In Sections 1.2 and 1.3, some of the results of the research and development work carried out at 3M using functionalized fluorinated oligomers are discussed.

1.2 Fluorinated Monomers and Building Blocks

1.2.1 Fluorinated Monomers

All industrial routes for the synthesis of the five major C2/C3 fluoromonomers are based on chlorination/fluorination of C1/C2 hydrocarbons, mostly including a de(hydro)chlorination step at high temperature (Scheme 1.1).

Some of these manufacturing processes are fairly energy consuming (e.g. the preparation of 1 ton of TFE requires >10 000 kWh). Also, special care has to be taken in producing and handling TFE owing to its tendency to self-decompose into carbon and tetrafluoromethane. In Table 1.1 an overview of monomers to produce fluoropolymers is given.

A key-intermediate in the preparation of vinyl ethers and their oligomers is hexafluoropropylene oxide (HFPO). HFPO is prepared from HFP via direct oxidation with oxygen, by electrochemical oxidation or by reaction with hypochlorides or hydrogen peroxide:

[FORMULA OMITTED]

HFPO reacts readily with nucleophiles; for example, in the presence of fluoride salts (e.g. NaF, KF, CsF) it forms the intermediate perfluoropropyl oxide salt, which reacts with the next HFPO to form an acid fluoride after elimination of a fluoride ion. This compound is the precursor for perfluoro(propyl vinyl ether) (PPVE), which is obtained by reaction with alkali/alkaline earth metal carbonates and subsequent pyrolysis (Scheme 1.2).

HFPO can also be oligomerized to produce higher molecular weight (up to 15 000 Da) perfluorinated polyethers having following general structure:

[FORMULA OMITTED]

Other important perfluorinated vinyl ethers are synthesized by reaction of fluorinated alkoxides with HFPO followed by pyrolysis; the fluorinated alkoxides are usually prepared in situ from the corresponding acid fluorides (Scheme 1.3).

An attractive, alternative route to perfluoro(methyl vinyl ether) (PMVE) is based on the reaction of perfluoromethyl hypofluoride and dichlorodifluoroethene followed by dehalogenation (Scheme 1.4). Solvay Specialty Polymers has mastered this synthesis and transferred it into large scale production.

Starting materials with functional groups can be prepared by direct or electrochemical fluorination (ECF) or by standard synthesis(Scheme 1.5).

The synthesis of comonomers for the preparation of perfluorinated amorphous polymers with high glass transition temperatures (Tg) involves multiple steps and has recently been described in detail (Figure 1.1).

1.2.2 Perfluoroalkyl Building Blocks

1.2.2.1 Chemical Routes

Fluorochemical building blocks containing a perfluorinated chain can be made on an industrial scale by methods including TFE/C2F5I telomerization, ECF and direct fluorination.

Telomerization allows the synthesis of oligomers of the type CnF2n+1-CH2CH2I, whereas ECF produces perfluoroalkyl carbonyl fluorides, RfCOF, or sulfonyl fluorides, RfSO2F. The perfluorinated chain may contain from one up to 16 carbon atoms. Telomer iodides and the carbonyl and sulfonyl fluorides can be converted on an industrial scale into alcohols and (meth)acrylate monomers. The acrylic monomers have the general structures shown in Scheme 1.6.

1.2.2.2 Environmental, Health and Safety Aspects

The first surfactants and textile treatments, containing perfluoroalkyl chains, were commercialized by 3M in the 1960s. Since then, major applications that were developed included fire-fighting agents, emulsifiers for fluoropolymers, oil and water repellents and paint and coating additives. Most of the fluorochemicals contained C6F13, C7F15 or C8F17 perfluoroalkyl groups. In the late 1990s, PFOS and related compounds were identified at parts per billion levels in the sera of the general population. In May 2000, 3M announced the manufacturing phase-out of "C8" chemistry. During the following years, new materials based on C4F9 technology that addressed the bioaccumulation and toxicity concerns associated with longer chain functional perfluoroalkyls, were developed and commercialized in selected markets. Environmental groups and governmental agencies are monitoring the use of higher perfluoroalkyl homologs and low molecular weight fluorochemicals very closely.

1.3 Functionalized Oligomers and Their Applications

1.3.1 Synthesis

Many of the functionalized fluorinated oligomers used on an industrial scale are made by ring-opening reactions of HFPO, photo-oxidation of fluoroolefins and telomerization of fluorinated (meth)acrylates with functional mercaptans.

1.3.1.3 Perfluoropolyether Derivatives

Perfluoropolyethers (PFPEs) are a class of low molecular weight polymers (500-15 000 Da) that were originally developed in the mid-1960s. Functionalized PFPEs are commercially available, for example under the trade names Krytox (E. I. DuPont de Nemours), Demnum (Daikin Industries) and Fomblin (Solvay Specialty Polymers). Their synthesis is summarized in Scheme 1.7, where X represents a COF group.

These PFPE carbonyl fluorides can be further converted into other functional groups, such as hydroxy, (meth)acrylate, nitrile and trialkoxyalkylsilane. A few examples are discussed below.

1.3.1.3 Functionalized Oligomeric (Meth)acrylates

The synthesis of functionalized fluorinated oligomers can be carried out by radical oligomerization of acrylic monomers in the presence of a functional mercaptan, such as 2-mercaptoethanol. A similar strategy was used to prepare oligomers with molecular weights ranging between 1500 and 10 000 Da and one or more functional groups, such as hydroxy, carboxy, amine or trimethoxysilane. The oligomers have an aliphatic backbone with a plurality (usually between 4 and 16) of pendant fluoroaliphatic groups and the majority of them are endcapped with the functional group(s). The oligomers contain a mixture of compounds with a range of repeating units; for example, if a monomer to mercaptan molar ratio of 4: 1 is used, a mixture of compounds with molar ratio ranging from 1: 1 to about 8: 1 is obtained after oligomerization. The synthesis is summarized in Scheme 1.8.

Using the same synthetic procedure, mixed co-oligomers can also be prepared using fluorine-free hydrophilic and hydrophobic comonomers. In the case of hydrophilic monomers containing alkylene oxide segments or an ionic group, such as salts of an acid (as present in, for example, sodium acrylate) or a quaternary ammonium group (as present in, for example, diethylaminoethyl methacrylate hydrochloride salt), surfactants can be prepared having an anionic, cationic, amphoteric or non-ionic character. Such surfactants provide efficient and effective lowering of the static and dynamic surface tension of liquids and increase the wetting of a coating on a substrate surface.

1.3.2 Derivatives of Functional Oligomers and Their Applications

Introduction

Functional oligomers can be reacted and blended with many different compounds through their functional group(s). For example, fluorinated oligomeric alcohols can be used in combination with isocyanates to make (poly)urethanes or in combination with carboxylic acids to make (poly)esters. Oligomeric acids can be condensed to (poly)amides. These condensates can be used as surface modifiers for commodity polymers such as poly(methyl methacrylate) (PMMA) or polyamide 6 (PA 6). In the following, examples and applications are discussed.

1.3.2.2 Oil- and Water-repellent Treatments for Fibrous Substrates

1.3.2.2.1 Introduction. Fluorochemical oil and water repellents for textile fabrics were discovered in the 1950s by researchers at 3M and, since then, many commercial products have been developed for a wide variety of surfaces by different companies. The repellent properties are the result of the low surface energy, typically between about 12 and 15 mN m-1, of a textile fabric treated with a fluorochemical repellent material. Water and oily substances will not be able to wet and spread on such a treated surface, resulting in water and oil repellency of the treated fabric(Figure 1.2).

Many fluorine-containing repellents are based on poly(meth)acrylates. These acrylic polymers can be visualized as consisting of pendant perfluoroalkyl groups (R) and hydrocarbon groups (R), an acrylic polymer backbone and non-fluorinated linkages between the two. The composition and ratio of the comonomers in such polymers affect the repellent properties. Comonomers with a crosslinking function, such as 2-hydroxyethyl acrylate, glycidyl methacrylate or N-methylolacrylamide, are used to increase the durability of the repellent treatment. Such copolymers can be represented as shown in Figure 1.3.

It was observed that organizing the fluorinated groups, Rf, into small domains improves their efficiency and effectiveness as oil and water repellents. This organization into fluorochemical domains can be achieved by using fluorochemical-functionalized oligomers and chemical methods to connect the oligomers to a backbone (Figure 1.4).

1.3.2.2.2 Isocyanate Derivatives of Oligomers. Much of the research and development work at 3M involved the combination of hydroxy-functionalized oligomers with isocyanates and fluorine-free mono-, di- or polymeric alcohols, amines, thiols and other isocyanate-reactive materials to form urethanes, ureas, thioureas or their polymeric analogs such as polyurethanes. These reactions are carried out in organic solvents, such as ethyl acetate, usually in the presence of catalysts such as certain Sn-compounds (e.g. dibutyltin dilaurate). Crosslinking of such urethane derivatives can be achieved by incorporating specific blocking agents such as oximes or imidazoles, thus forming thermolabile urethane groups. These thermolabile groups decompose at the curing temperature of the fabric treatment, typically 150-170 °C, generating in situ isocyanate functionalities that will react with any hydroxy, amino or carboxy group present on the fiber surface, creating a chemical bond between the textile fabric and the fluorochemical agent, resulting in improved laundering and dry-cleaning resistance.

An interesting class of isocyanate-derived repellents are polycarbodiimides, since the carbodiimide group, -N=C=N-, itself can react with functional groups present at the surface of the textile fabric. Polycarbodiimides containing fluorinated oligomer segments were prepared and found to have very good durable repellent properties without the use of an isocyanate blocking group.

Another important finding was the discovery of functionalized fluorinated spacer oligomers, prepared by radical oligomerization of spacer monomers with functional mercaptans. The fluorinated spacer monomers can be prepared by combining a fluorinated alcohol, e.g. C4F9 SO2N(CH3)CH2CH2OH, with a diisocyanate, e.g. MDI (4,4'-diphenylmethane diisocyanate) and a hydroxy-terminated alkyl(meth)acrylate, such as 2-hydroxyethyl methacrylate.

Fluorochemical textile treatments provide excellent oil and water repellency and stain-repellent finishes, but for the release of soil and stains, water needs to displace the contaminants and the laundering detergent must be able to wet the fabric. Treatments with both hydrophilic and hydrophobic/oleophobic segments were developed, which in dry conditions provide repellent properties (due to the fluorochemical tails), but in water the structure "inverts" and exposes the hydrophilic parts, resulting in good soil-release ("flip-flop" mechanism).

1.3.2.3 Oil- and Water-repellent Treatments for Siliceous Surfaces

1.3.2.3.1 Introduction. By applying fluorinated compounds, especially fluorinated trialkoxysilanes, to siliceous surfaces, such as glass or ceramics, such substrates can be given a low surface energy, typically around 10-15 mN m-1, even when solutions with very low concentrations of 0.01-0.2% by weight are used. Very high thermal and oxidative stabilities were also observed. Fluorinated silanes have the ability to form chemical bonds with the hydroxy groups present on the glass through the formation of Si-O-Si bonds.

1.3.2.3.2 PerfIuoro(poIyether silanes). Perfluoro(polyether silanes) can be easily prepared by reaction of the corresponding esters with aminopropyltrialkoxysilanes or the corresponding alcohols with isocyanatopropyltrialkoxysilanes. Some structures are shown in Figures 1.5 and 1.6.

These silanes can be easily applied to siliceous surfaces, such as shower panels or bathroom ceramics, by applying dilutions in alcohols, such as ethanol or 2-propanol, in combination with catalytic amounts of acid. In a first step, the trialkoxysilanes are hydrolyzed into silanols, which then undergo condensation reactions (silanols reacting with themselves) and crosslinking, where the fluorochemical is chemically bonded to the hydroxy groups of the siliceous surface. The PFPE layer is very thin (about 20-100 nm) and provides excellent repellent and easy-to-clean properties and very good durability against aggressive chemicals, such as acids or bases, and against mechanical abrasion.

Methods for aqueous delivery of PFPE-silanes were also developed. One method consists of making a non-aqueous concentrate containing the PFPE-silane and a fluorosurfactant, diluting the concentrate in water and applying the aqueous formulation to the siliceous surface. Another way is to prepare cationic perfluoro(polyether silanes), which are readily soluble or dispersible in water, and applying them to the siliceous surface followed by room temperature drying and curing.

1.3.2.4. Fluoropolymers with Low Glass Transition Temperatures (Tg)

1.3.2.4.1 Introduction. A wide variety of fluoropolymers have been developed and produced on an industrial scale for a broad range of applications. However, except for fluorosilicones, fluoropolymers with a low Tg are not widely available.

(Continues...)

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Dettagli dell?edizione

• Editore: Royal Society of Chemistry
• Data di pubblicazione: 2016
• Lingua: Inglese
• ISBN 10: 1782629165
• ISBN 13: 9781782629160
• Rilegatura: Copertina rigida
• Numero di pagine: 450
• Redattore: Ameduri Bruno, Sawada Hideo, Masuda Toshio
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile