Semiconducting Polymers: Controlled Synthesis and Microstructure (Polymer Chemistry Series, 21, Band 21) - Hardcover

Hardcover

ISBN 10: 1782620346 ISBN 13: 9781782620341

Verlag: Royal Society of Chemistry, 2016

Inhaltsangabe

Semiconducting polymers are of great interest for applications in electroluminescent devices, solar cells, batteries and diodes. In recent years vast advances have been made in the area of controlled synthesis of semiconducting polymers, specifically polythiophenes. Edited by one of the leaders in the area of polythiophene synthesis, this new book will bring the field up to date with more recent models for understanding semiconducting polymers. The book is separated into two main sections, the first will introduce the advances made in polymer synthesis, and the second chapter will focus on the microstructure and property analysis that has been enabled because of the recent advances in synthetic strategies.

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Über die Autorin bzw. den Autor

University of Toronto University of Washington, USA Chinese Academy of Sciences, PRC Kanagawa University, Japan Imperial College London

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Semiconducting polymers are of great interest for applications in electroluminescent devices, solar cells, batteries and diodes. In recent years vast advances have been made in the area of controlled synthesis of semiconducting polymers, specifically polythiophenes. The book is separated into two main sections, the first will introduce the advances made in polymer synthesis, and the second chapter will focus on the microstructure and property analysis that has been enabled because of the recent advances in synthetic strategies.
Edited by one of the leaders in the area of polythiophene synthesis, this new book will bring the field up to date with more recent models for understanding semiconducting polymers. The book will be applicable to materials and polymers chemists in industry and academia from postgraduate level upwards.

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Semiconducting Polymers

Controlled Synthesis and Microstructure

By Christine Luscombe

The Royal Society of Chemistry

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

ISBN: 978-1-78262-034-1

Contents

Section I: Controlled Synthesis of Semiconducting Polymers, 
Chapter 1 Controlled Synthesis of Conjugated Polymers in Catalyst-transfer Condensation Polymerization: Monomers and Catalysts T. Yokozawa and Y. Ohta, 3, 
Chapter 2 Controlled Chain-growth Synthesis of Conjugated Polymers: Moving Beyond Thiophene C. R. Bridges and D. S. Seferos, 38, 
Chapter 3 Application of Catalyst Transfer Polymerizations: From Conjugated Copolymers to Polymer Brushes Yanhou Geng and Aiguo Sui, 85, 
Chapter 4 Controlled Synthesis of Chain End Functional, Block and Branched Polymers Containing Polythiophene Segments Tomoya Higashihara and Mitsuru Ueda, 121, 
Section II: Microstructure of Semiconducting Polymers, 
Chapter 5 Characterization of Polymer Semiconductors by Neutron Scattering Techniques Gregory M. Newbloom, Kiran Kanekal, Jeffrey J. Richards and Lilo D. Pozzo, 165, 
Chapter 6 Structural Control in Polymeric Semiconductors: Application to the Manipulation of Light-emitting Properties Ioan Botiz, Cosmin Leordean and Natalie Stingelin, 187, 
Chapter 7 Structure and Order in Organic Semiconductors Chad R. Snyder, Dean M. DeLongchamp, Ryan C. Nieuwendaal and Andrew A. Herzing, 219, 
Subject Index, 275, 

CHAPTER 1

Controlled Synthesis of Conjugated Polymers in Catalyst-transfer Condensation Polymerization: Monomers and Catalysts

T. YOKOZAWA AND Y. OHTA

Introduction

Semiconducting p-conjugated polymers were first synthesized by the chemical and electrochemical oxidative polymerization of electron-rich aromatic species such as pyrrole, thiophene, and aniline. This polymerization method is still widely used in, for example, the modification of electrodes. Yamamoto later reported organometallic polycondensation reactions involving cross-coupling reactions catalyzed by transition metals, such as the Kumada-Tamao coupling of organo-magnesium halides, Negishi coupling of organo-zinc halides, and Sonogashira coupling of acetylenic compounds, in addition to the polycondensation of dibromoarenes with an equimolar Ni complex (Yamamoto coupling). The Pd-catalyzed polycondensations of organo-borons (Suzuki-Miyaura coupling) and organo-stannanes (Stille coupling) have also been developed by other researchers. As these polymerizations proceeded in a non-chain reaction manner, research was focused on synthesizing high molecular weight p-conjugated polymers by changing the coupling reactions and polymerization conditions rather than on controlling molecular weight, polymer end-groups, and dispersity, which was believed to be achievable only by means of "living" chain polymerization using vinyl monomers and cyclic monomers.

In 2004, our research group and McCullough and coworkers independently found that bromothiophenemagnesium chloride and its zinc chloride counterpart underwent chain polymerization with an Ni catalyst to afford poly(3-hexylthiophene) (P3HT) with a controlled molecular weight, low dispersity, and defined polymer ends. This finding was made during the course of research on the condensative chain polymerization of aromatic polyamides and the synthesis of regioregular P3HT, respectively. We proposed that chain polymerization involves the intramolecular transfer of the catalyst to the polymer C-Br ends after reductive elimination and we named this type of polymerization catalyst-transfer condensation polymerization (CTCP). This finding opened up a new area of research, aimed on extending CTCP to other coupling polymerizations and applying it to develop organic electronic devices, such as photovoltaics and field-effect transistors. This chapter focuses on the monomers and catalysts used for catalyst-transfer Kumada-Tamao coupling polymerization, Suzuki-Miyaura coupling polymerization, and other coupling polymerizations. p-Conjugated polymer architectures such as block copolymers, obtained by virtue of CTCP, are reviewed in Chapter 3.

1.2 Kumada-Tamao Coupling Polymerization of Grignard Monomers

1.2.1 Background and Discovery

We developed condensative chain polymerization by the activation of the polymer end-group based on a difference of substituent effects between the monomer and the polymer. An example of condensative chain polymerization for the synthesis of a well-defined aromatic polyamide is shown in Figure 1.1a. The amide anion of monomer 1 deactivates the ester moiety through its strong electron-donating resonance effect, which serves to suppress self-condensation. Monomer 1 then selectively reacts with the polymer end-group, which has a weaker electron-donating amide linkage at the para position, resulting in chain polymerization. Similar substituent effects are known in organometallic chemistry; for example, an electron-donating group on an aromatic halide retards oxidative addition with a zero-valent transition metal catalyst. We utilized this chemistry for the Pd-catalyzed condensative chain polymerization of bromophenoxide 2 and carbon monoxide. Chain polymerization proceeded until the middle stage of polymerization and transesterification occurred in the final stage, resulting in a non-chain behavior (Figure 1.1b).

We attempted to conduct a simpler Ni-catalyzed condensative chain polymerization of bromothiophenemagnesium chloride 3 on the basis of substituent effects, because bond-exchange reactions such as transesterification do not occur on the polythiophene backbone. Osaka and McCullough reported that the Ni-catalyzed Kumada-Tamao coupling polymerization of 3 yielded regio-regular P3HT with superior electrical properties. We similarly anticipated that the Ni0 catalyst would insert selectively into the terminal C-Br bond of the polymer chain, rather than the C-Br bond of monomer 3, because the strong electron-donating chloromagnesio moiety of 3 would deactivate the C-Br bond for oxidative addition (Figure 1.1c). The polymerization of 3 with Ni(dppp)Cl2 (dppp = 1,3-bis(diphenylphosphino)propane) at room temperature showed chain polymerization behavior; the molecular weight increased in proportion to monomer conversion, and extension of the polymer chain took place upon further addition of the monomer to the reaction mixture. At the same time, McCullough and coworkers reported the Ni-catalyzed chain polymerization of the zinc chloride counterpart and 3.

However, molecular weight was not controlled by the addition of active aryl halides bearing an electron-withdrawing group, implying that the anticipated condensative chain polymerization based on a change in the substituent effect was not involved in this polymerization. After a detailed study of the mechanism, four important points were clarified: (1) the polymer end-groups are uniform among molecules - one end-group is Br and the other is H; (2) the propagating end-group is a polymer-Ni-Br complex; (3) one Ni molecule forms one polymer chain; and (4) the chain initiator is a dimer of 3 formed in situ. On the basis of these results, we proposed that the Ni0 catalyst is inserted into the intramolecular C-Br bond after transmetallation of the polymer-Ni-Br complex with 3 and reductive elimination during propagation (Figure 1.1d). The intramolecular transfer of Ni catalysts has been reported in organic chemistry; van der Boom and coworkers demonstrated that the Ni atom on an ?2-C=C complex of bromostilbazole underwent intramolecular transfer...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2016
• Sprache: Englisch
• ISBN 10: 1782620346
• ISBN 13: 9781782620341
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 278
• Herausgeber: Luscombe Christine
• Kontakt zum Hersteller: preigu GmbH & Co. KG; mail@preigu.de; ; Lengericher Landstr. 19; Osnabrück; Niedersachsen; 49078; Deutschland