5144 | Chem. Soc. Rev., 2016, 45, 5144--5146 This journal is©The Royal Society of Chemistry 2016

Cite this: Chem. Soc. Rev., 2016,

45, 5144

Smart Inorganic Polymers

Anne-Marie Caminade,*a Evamarie Hey-Hawkinsb and Ian Mannersc

Polymers have a broad range of propertiesand play an essential and ubiquitous rolein everyday life. Most of these materialsare organic polymers, incorporating intheir structure carbon and hydrogen, and

also, in most cases, nitrogen and oxygen.Inorganic polymers – that we define aspolymers incorporating inorganic elementsin their backbone, either alone or in combi-nation with carbon – are much less known,with the notable exception of polysiloxanes,also known as silicones. Inorganic polymersare a hot topic and have attracted broadand persistent interest from both academicand industrial researchers due to theirspecial chemical and physical properties,and potential applications. A current EU-funded COST Action (CM1302) is dedicated

to smart inorganic polymers (SIPs); 7contributions to this special issue are writtenby members of this network. This specialissue will cover in 5 Tutorial Reviews and6 Reviews, contributions about polymersincluding in their structure main groupelements (P, B, Sn, Si) and/or metal frame-works, in particular transition metals. Thevast development and rapid expansion ofinorganic polymer research, from synthesesto applications, especially in nano-technologies and for biomedical uses areemphasized in many of these reviews.

a CNRS, LCC (Laboratoire de Chimie de

Coordination), 205 Route de Narbonne, BP 44099, F-

31077 Toulouse Cedex 4, France. E-mail: anne-

marie.caminade@lcc-toulouse.frb Institute of Inorganic Chemistry, Universitat Leipzig,

Johannisallee 29, 04103 Leipzig, Germany.

E-mail: hey@uni-leipzig.dec School of Chemistry, University of Bristol, Bristol,

BS8 1TS, UK. E-mail: ian.manners@bristol.ac.uk

Anne-Marie Caminade

Anne-Marie Caminade is theDirector of Research ExceptionalClass at CNRS and head of the‘‘Dendrimers and Heterochemistry’’group at LCC-Toulouse. After twoPhDs in Toulouse and two post-docs (IFP-Paris, Von Humboldtfellow in Saarbrucken), she wasrecruited by CNRS in 1985. Shehas developed several aspectsof phosphorus chemistry (lowcoordinated compounds, transitionmetal coordination, macrocycles).Her current research interest is

dendrimers, in particular those she designed in 1993, and on theiruses as catalysts, for nanomaterials and in biology/nanomedicine.She is the co-author of about 420 publications, 40 book chapters and30 patents (h index 58).

Evamarie Hey-Hawkins

Evamarie Hey-Hawkins receivedher doctoral degree (1983) at theUniversity of Marburg, Germany.After posts at the University ofSussex, UK, the University ofWestern Australia and the ANU,Canberra, Australia, she returnedto Germany (Marburg, 1988). From1988–1990 she was a ResearchAssociate at the Max PlanckInstitute for Solid State Research,Stuttgart, Germany, then aHeisenberg fellow at TechnicalUniversity Karlsruhe, Germany

(1990–1993). Since 1993, she has been the Chair in InorganicChemistry at Universitat Leipzig, Germany. Since October 2013,she has been the Chair of a COST Action on ‘‘Smart InorganicPolymers’’ (CM1302, SIPs, www.sips-cost.org). Her scientific interestsare in the field of organophosphorus chemistry, biologically activeboron compounds and transition metal complexes for applications incatalysis and materials science.

DOI: 10.1039/c6cs90086k

www.rsc.org/chemsocrev

Chem Soc Rev

EDITORIAL

Publ

ishe

d on

20

Sept

embe

r 20

16. D

ownl

oade

d on

15/

10/2

016

16:4

3:40

.

View Article OnlineView Journal | View Issue

This journal is©The Royal Society of Chemistry 2016 Chem. Soc. Rev., 2016, 45, 5144--5146 | 5145

Polyphosphazenes are inorganic poly-mers with a phosphorus–nitrogen back-bone, and have a long history: they werefirst reported as early as the 1890s. Currently,there are significant ongoing developmentsof polyphosphazenes for uses as flameretardants, as soft materials, or in the bio-medical field. The tutorial review by IanTeasdale et al. (DOI: 10.1039/C6CS00340K)provides an introduction to the basics ofthe synthetic chemistry of polyphospha-zenes, with some of the recent advancesin their chemical synthesis. This includesnot only the synthesis of polyphospha-zenes with controlled molecular weightsand polydispersities, but also the synthesisof branched structures, block copolymers,and supramolecular architectures.

p-Conjugated polymers and oligomersincorporating heteroatoms, such as poly-thiophenes, have emerged as promisingmaterials to build electronic flexible devicessuch as organic light emitting diodes(OLEDs), organic field effect transistors(OFETs) or organic photovoltaic cells(OPV). New types of p-conjugated moietiesincorporating phosphorus derivatives, inparticular phospholes, should furtherexpand this field. The review articleauthored by Muriel Hissler et al. (DOI:10.1039/C6CS00257A) describes thesynthesis of p-conjugated phospholes andtheir incorporation into devices for organicelectronic materials.

Icosahedral boron clusters display manypeculiar characteristics, such as uniquestabilities and geometric features. The

development of hybrid organic–inorganicp-conjugated polymers, and of silane,siloxane and coordination polymersincorporating icosahedral boron clustershas received considerable academic andtechnological interest, as emphasized inthe tutorial review proposed by ClaraVinas et al. (DOI: 10.1039/C6CS00159A).The inclusion of boron clusters both inp-conjugated and non-conjugated polymers,as doping agents in conducting organicpolymers, or as a doping agent bonded tothe main chain of the polymer for self-repairing are among the key featuresalready reported. The particular propertiesof boron clusters may impart unconven-tional properties to polymers, if clustersare incorporated either non-covalently,or as part of the main chain of thepolymer, or as pendant groups from themain chain.

Dendrimers are hyperbranched macro-molecules, reminiscent of conventionalpolymers, as they are constituted ofrepetitive monomeric units. However,they are synthesized step-by-step, and notby polymerization reactions, hence ensuringa perfectly defined 3D structure. The tutorialreview by Anne-Marie Caminade (DOI:10.1039/C6CS00074F) concerns inorganicdendrimers, and more precisely dendri-mers incorporating either phosphorusor silicon at each branching point, inparticular polyphosphorhydrazone andpolycarbosilane dendrimers. It describesthe main properties of both families ofdendrimers in the fields of catalysis,

materials and biology/nanomedicine, withemphasis on the most recent and promisingproperties.

Ferrocenes are prototypical metallocenesthat undergo a reversible one-electronoxidation at a low potential. Covalentlyincorporating ferrocenes into a polymercan deeply modify its physical andchemical properties. This can be donein two ways, by incorporation into themain chain of the polymer (backbone) orby attachment as pendant groups to thepolymer backbone. Two reviews discussthese topics independently. The reviewby Ian Manners et al. (DOI: 10.1039/C6CS00155F) covers in depth polyferro-cenylsilanes, main chain organosiliconmetallopolymers consisting of alternatingferrocene and organosilane units. Syntheticpathways towards polyferrocenylsilanehomopolymers and polyferrocenylsilaneblock copolymers are shown, essentiallyby ring-opening polymerisations of sui-table precursors. For both homo- andco-polymers, the properties and applica-tions are largely discussed, such as highrefractive index materials, electro-actuated redox-active gels, fibres, films,nanoporous membranes, precursors tonanostructured magnetic ceramics, andetch resists to plasmas and other radiation.Applications in nanolithography, nano-templating, and nanocatalysis, as functionalmicelles with core–shell structures, for‘‘living crystallisation-driven self-assembly’’ in solution – controlled methodsof assembling block copolymers into 1D or2D structures – are also given. Polymersbearing pendant ferrocenes, with potentialapplications in electrochemistry, electro-nics, optoelectronics, catalysis, and sensing,as precursors for patterned metal oxidesand alloys, and for biology constitute thetopic of the tutorial review by RudolfPietschnig (DOI: 10.1039/C6CS00196C).It is also shown in this review that theredox properties of the pendant ferrocenylunits may modify the charge, polarity,colour and hydrophilicity of the polymers,and of polymer functionalized interfacesand networks.

Polystannanes are the only type of poly-mers comprising a backbone exclusivelyconstituted of covalently bound metalatoms, based on SnR2 units. In his tutorialreview (DOI: 10.1039/C6CS00168H), Walter

Ian Manners

Ian Manners received his PhD from the University ofBristol, conducted postdoctoral work in Germany andthen in the USA, and joined the University of Toronto,Canada as an Assistant Professor in 1990. He was madeFull Professor in 1995 and a Canada Research Chair in2001. In 2006 he returned to Bristol to take up a Chair inInorganic, Macromolecular and Materials Chemistry andan EU Marie Curie Chair. His awards include a SloanFellowship (from the US), the Steacie Prize (fromCanada), the RSC Award in Main Group Chemistry, theRSC Peter Day Award for Soft Matter Materials Chemistry,and a Humboldt Research Award from Germany. He is anelected member of both the Canadian and the BritishNational Academies of Science. His work is documentedin >600 papers and 4 books and has been presented in ca.500 invited lectures worldwide.

Editorial Chem Soc Rev

Publ

ishe

d on

20

Sept

embe

r 20

16. D

ownl

oade

d on

15/

10/2

016

16:4

3:40

. View Article Online

5146 | Chem. Soc. Rev., 2016, 45, 5144--5146 This journal is©The Royal Society of Chemistry 2016

Caseri describes first the synthesis and thechemical and physical characterization ofpolystannanes, in particular with 119SnNMR spectroscopy. Delocalized s-electronsare a rare phenomenon, observed in poly-stannanes, and are responsible for theircharacteristic yellow colour. Polystannanesoffer a valuable and rare mixture of materialproperties, such as for instance, a combi-nation of semiconductivity and adequatethermal stability with the ease of proces-sing, polymer orientation and filmformation.

Metallopolymers are constituted ofmetal centers incorporated into the back-bone of polymers. Three reviews discussseveral aspects of the broad range ofmetallopolymers. The basic concepts,design and synthetic strategies leadingto various types of metallopolymers aregathered in the review authored byUlrich S. Schubert et al. (DOI: 10.1039/C6CS00182C). A large part of the reviewalso concerns the overview and scope ofthe techniques available for characterizingthese organometallic and coordinationpolymers which potentially possess dynamicbehaviour. Metallopolymers have manyproperties; the review by Cheuk-Lam Ho,Zhen-Qiang Yu and Wai-Yeung Wong

(DOI: 10.1039/C6CS00226A) discussesthe properties of a special class of metal-lopolymers, the polymetallaynes, in whichmetal atoms (mainly transition metals)are embedded into p-conjugated polymerchains. This review summarizes thestructure–property–function relationshipsof polymetallaynes, in particular in thefields of electrical semi-conductivity,photo-/electroluminescence, photovoltaics,non-linear optics, liquid crystallinity, andchemo-sensing, depending on the tran-sition metals and the structure of theligands used. The most recent progressconcerning biomedical applications ofmetallopolymers is gathered in thereview by Yi Yan, Chuanbing Tang et al.(DOI: 10.1039/C6CS00026F). Inspired bythe advances of metal-containing smallmolecular drugs, about 30 differentmetals, most of them transition metals,have been introduced into polymericframeworks. This review summarizesbiomedical applications of metal-containing polymers, in particular asdrug delivery vehicles, as drugs (anti-cancer, photodynamic therapy andradiotherapy) and biocides (antimicrobialand antiviral agents), as biosensors, andfor bioimaging.

A further step forward for metallopo-lymers concerns metal–organic frame-works (MOFs). MOFs are a subclass ofcoordination polymers, organized in (2D)3D structures containing potential voids.Single crystals of some types of MOFsmay control photoexcitation under theinfluence of light, being nonlinear andquantum metamaterials, as shown in thereview by Evamarie Hey-Hawkins, AlexandrV. Vinogradov et al. (DOI: 10.1039/C6CS00395H). The review begins with anintroduction to nonlinear optics (NLO), inparticular applied to the case of materials.Based on these data, the nonlinear opticalproperties of metal–organic structures arestudied. Synthetic approaches used forobtaining MOFs with improved qualityand the desired properties in the field ofnon-linear optics are also described.

Taken altogether the reviews and tutorialreviews of this special issue about smartinorganic polymers draw an impressionist(and impressive) picture, with an infinitenumber of chemical structures, and analready huge number of properties. Withthis special issue, we hope to stimulatefurther research and yet more innovativeapplications for these highly interestingmultifaceted materials.

Chem Soc Rev Editorial

Publ

ishe

d on

20

Sept

embe

r 20

16. D

ownl

oade

d on

15/

10/2

016

16:4

3:40

. View Article Online