inorganic and organometallic polymers

Download Inorganic and organometallic polymers

Post on 02-Mar-2017

214 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Inorganic and organometallic polymers

    Kevin J. T. Noonan and Derek P. Gates*DOI: 10.1039/b612872f

    The synthesis of macromolecules composed partially or entirely of inor-ganic elements in the main chain is an area of widespread interest. Thisreport summarizes the many advances that were made in the area ofinorganic polymer science in 2006.

    Highlights

    Major accomplishments in the synthesis of inorganic polymers include: the observa-

    tion of molecular weight doubling when polysilanes are synthesized in chiral

    solvents, the synthesis of PH polyphosphazenes, the development of polyphos-

    phole-based sensors, the ring-opening polymerization of phosphirenes, the living

    anionic polymerization of PQC bonds, the ring-opening polymerization of [1]sila-trochrocenophanes, and the development of palladium-containing polymers as

    supramolecular cruciforms.

    1 Introduction

    The synthesis of macromolecules composed partially or entirely of inorganic

    elements in the main chain is an area of widespread interest. A major challenge

    facing researchers in this area is the development of general synthetic methods to

    link inorganic elements into long chains. Despite these hurdles, researchers are

    motivated to develop polymers containing main group elements or transition metals

    due to their novel properties and possible applications.

    In this article, the 2006 literature in the area of inorganic and organometallic

    polymers shall be surveyed. This report complements previous articles in this series,1

    and is divided into eight sections beginning with this introductory part. The next

    subsection will give an overview of recent books, reviews and highlight articles that

    have been published in the area. This is followed by three subsections devoted to the

    well-established polysiloxanes (silicones), polysilanes, and polyphosphazenes. This is

    followed by a summary of advances in the development of new types of macro-

    molecules composed partially or entirely of main group elements. A section will then

    be devoted to the growing field of ferrocene and related organometallic polymers.

    The final section will highlight progress in the synthesis of macromolecules contain-

    ing transition metals within the main chain.

    In this review, emphasis will be placed on synthetic advances in the development

    of linear macromolecules containing main group elements or transition metals

    within the main chain.

    Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver,Canada BC V6T 1Z1

    Annu. Rep. Prog. Chem., Sect. A, 2007, 103, 407427 | 407

    This journal is c The Royal Society of Chemistry 2007

    REVIEW www.rsc.org/annrepa | Annual Reports APu

    blis

    hed

    on 2

    2 Ju

    ne 2

    007.

    Dow

    nloa

    ded

    by U

    nive

    rsity

    of

    Illin

    ois

    at C

    hica

    go o

    n 28

    /10/

    2014

    01:

    59:1

    3.

    View Article Online / Journal Homepage / Table of Contents for this issue

    http://dx.doi.org/10.1039/b612872fhttp://pubs.rsc.org/en/journals/journal/IChttp://pubs.rsc.org/en/journals/journal/IC?issueid=IC007103

  • 2 Books and reviews of inorganic polymer science

    A book entitled Metal-Containing and Metallosupramolecular Polymers and Materi-

    als has been published in 2006 as part of the ACS symposium series.2 The editors,

    Schubert, Newkome, and Manners have assembled a wonderful collection of articles

    from a variety of leading researchers in the field. An excellent monograph entitled

    Frontiers in Transition Metal-Containing Polymers has appeared which features

    chapters written by leaders in the field.3 A special issue of Current Organic Chemistry

    has appeared on organophosphorus chemistry in which phosphorus-containing

    macrocycles and dendrimers are described.4

    An interesting review of the literature on the Pt content in commercial silicones

    and its implications for biomedical applications has appeared.5 The use of acyclic

    diene metathesis (ADMET) to prepare siliconcarbon hybrid materials has been

    highlighted.6 Divinylarene-silylene copolymers have been reviewed in a Chemical

    Communications feature article.7 A review of Wurtz-type coupling to synthesize

    polysilanes in high yields has been compiled by Jones and Holder.8 Weak non

    covalent Si FC interactions of fluorosilane polymers have been highlighted.9Several reviews of phosphazene macromolecules have appeared on topics ranging

    from ion conductivity,10 the use of polyphosphazenes as hydrophobic surfaces,11 to

    recent developments of metal-containing phosphazene macromolecules.12

    New directions in main group polymers have been reviewed fairly extensively in

    2006. A comprehensive review of p-conjugated phosphorus-containing materials byBaumgartner and Reau has been published.13 A review of the synthesis and

    properties of bithiophenes containing heteroatoms has appeared.14 Jakle has high-

    lighted the incorporation of Lewis acidic boron centres into macromolecules.15 Two

    reviews highlighting recent advances in dehydrocoupling as a route to polymers

    possessing inorganic elements have been published.16,17

    Advances in ring opening polymerization (ROP) and supramolecular polymer self

    assembly has been highlighted.18 An overview of the recent advances in transition

    metal containing conjugated polymers has appeared.19 Conjugated organometallic

    polymer networks and metal-containing supramolecular architectures have been

    reviewed.20,21 Organometallic structures p bonded to quinonoids forming coordina-tion networks has been highlighted.22,23 Using metallo-supramolecular initiators for

    controlled polymerization has been reviewed.24 An article on organometallic poly-

    mer nanostructures has appeared.25 Reviews on phosphorus-, metal- and silicone-

    containing dendrimers have appeared in the literature.2632

    3 Polysiloxanes (silicones) and related polymers

    The field of polysiloxanes is the most mature area of inorganic polymer science and a

    large number of papers were published in 2006. Consequently, there is not enough

    space to highlight all the developments in this vast area and this section will focus on

    advances in the synthesis of novel silicone macromolecules.

    Weber and coworkers have prepared a monomer containing a tricyclic and

    tetracyclic siloxane ring (1) and have selectively polymerized the tricyclic ring using

    anionic and cationic ROP to prepare 2.33 This interesting development represents the

    first selective polymerization of one ring of a bicyclic siloxane monomer and could

    prove to be a valuable route to copolymers and crosslinked macromolecules.

    Polystyrene-polysiloxane multiblock copolymers 3 with moderate molecular weight

    (ca. 25 000 g mol1) were synthesized from hydrosilylation coupling and were

    408 | Annu. Rep. Prog. Chem., Sect. A, 2007, 103, 407427

    This journal is c The Royal Society of Chemistry 2007

    Publ

    ishe

    d on

    22

    June

    200

    7. D

    ownl

    oade

    d by

    Uni

    vers

    ity o

    f Il

    linoi

    s at

    Chi

    cago

    on

    28/1

    0/20

    14 0

    1:59

    :13.

    View Article Online

    http://dx.doi.org/10.1039/b612872f

  • characterized by differential scanning calorimetry (DSC) and scanning electron

    microscopy (SEM).34 Poly(ethylene oxide)-polydimethylsiloxane-poly(ethylene

    oxide) triblock copolymers were observed to form aggregates with a variety of

    morphologies that can be controlled by altering the self-assembly conditions.35

    Two different strategies have been developed for the preparation of polydi-

    phenylsiloxane-polydimethylsiloxane-polydiphenylsiloxane triblock copolymers.36

    The anionic ring-opening polymerization (ROP) of hexamethylcyclotrisiloxane

    (D3) using the bifunctional initiator Li2(Ph2SiO2) followed by treatment with

    hexaphenyltrisiloxane affords polymer 4. In the second strategy, the hydrosilylation

    of vinyl-terminated polydiphenylsiloxane with a,o-bis(hydrido)polydimethylsilox-ane is employed to afford triblock copolymer 5. The number average molecular

    weights (Mn) for these novel copolymers ranged from 8800 g mol1 to 31 300 g

    mol1 with polydispersity indices (PDIs) ranging from 1.41.8.

    Annu. Rep. Prog. Chem., Sect. A, 2007, 103, 407427 | 409

    This journal is c The Royal Society of Chemistry 2007

    Publ

    ishe

    d on

    22

    June

    200

    7. D

    ownl

    oade

    d by

    Uni

    vers

    ity o

    f Il

    linoi

    s at

    Chi

    cago

    on

    28/1

    0/20

    14 0

    1:59

    :13.

    View Article Online

    http://dx.doi.org/10.1039/b612872f

  • Alternating copolymers (8) were obtained from the hydrosilylation of the divinyl

    monomer 6 with the SiH terminated oligosiloxane 7.37 The coupling of oligosilane 7

    (21004000 g mol1) with 6 afforded the copolymer 8 with molecular weights up to

    78 100 g mol1.

    Poly(dimethylsiloxane) zinc and sodium ionomers (0.31.3 mol% of metal) have

    been prepared and their gel formation has been described.38 Chojnowski and

    410 | Annu. Rep. Prog. Chem., Sect. A, 2007, 103, 407427

    This journal is c The Royal Society of Chemistry 2007

    Publ

    ishe

    d on

    22

    June

    200

    7. D

    ownl

    oade

    d by

    Uni

    vers

    ity o

    f Il

    linoi

    s at

    Chi

    cago

Recommended

View more >