Oligomers, polymers and copolymers via metal catalysis

Objectif

A.GENERAL BACKGROUND

A1: Why a COST action for this topic ?

The aim of this Action is to bring together scientists with complementary expertises in the field of oligomerisation, polymerisation and copolymerisation of unsaturated hydrocarbons via metal catalysis to obtain polymeric materials with new or improved performance parameters. The field is gaining momentum and academies are starting to respond to the call for basic expertise in single-site transition metal polymerisation catalysis from companies. Polymerisation catalysts based on soluble or supported early and late transition elements or lanthanides and actinides are attracting much interest due to their potential for tolerating various heteroatom functionalities. This feature actually opens up the possibility of processing polar monomers as well as various cheap feedstocks such as CO, CO2, ROH, RCN, etc. for the obtainment of various functionalised polymers.

The great variety of available monomers and functional group requires a systematic design of specifically tailored catalysts which may be carried out exclusively by a group of scientists with complementary expertises who agree to collaborate together. To achieve this goal, the Action should include organometallic, inorganic, organic, polymer, and physical science each with their specific aims and objectives but strongly interacting in methodology, approach and final goal, namely the design of new single-site polymerisation catalysts and of new polymeric materials, the characterisation and processing of polymers and the optimisation of manufacturing processes featured by minimal environmental impact. In order to derive feasible industrial polymerisation processes, close co-operation between chemists and engineers will also be necessary. The choice of the form of catalysts to be improved and optimised at the laboratory stage depends indeed on the reactor in which they should be used. In this respect, many factors must be considered, which include catalyst activity, selectivity and deactivation.

The design of catalysts and catalytic polymerisation constitute the heart of modern chemical industry as this approach allows for the stereocontrol of known polymers - and thus improves their physical properties - and the discovery of new functional and block polymers, e. g. of new materials with specific properties.

Fundamental and applied research in this field constitutes a challenge for European industry. Current competition, at both the industrial and academic level, is taking place between Europe, the USA and Japan in the field of single-component metal catalysts for C-C bond forming processes in polymerisation.

This challenge is of primary importance to maintain and improve the competitiveness of the european chemical industry involved in the field of polymeric materials. In Europe, most important petrochemical companies possess a division eager to develop catalysts, polymerisation reactions and polymers. A preliminary study reveals that close to 100 European groups are working at the boundary of this topic in expansion. However, one major problem is that, at present, activities are too fragmented, which hampers the required developments. A massive effort in this area is thus absolutely essential.

A very important first step in this direction will be formed by a COST-action creating an environment in which emerging programs in the different European countries could be mutually beneficial so as to compete under the same conditions with analogous American and Japanese programs. This Action may also serve as an initial step towards the formation of a scientific network for the concertation of research efforts in this field in Europe and to further the interest of young researchers. It is clear that COST-funding by itself is not sufficient to start and support an European program on "Oligomers, Polymers and Copolymers via Metal Catalysis". It will stimulate, however, the cooperation and contacts between scientists working in this area and provide strong impetus for making EU networks in which groups with the requested complementary skills will successfully collaborate. It will also be an incentive for further cooperation in this area between academics and industries as well as science foundations of different countries.

The keywords for this action are: monoalkene homo- and copolymerisation, olefin metathesis, ATRP, metallocene catalysts, transition metal catalysts, actinide and lanthanide catalysts, supported catalysts, polyethylenes, polypropylenes, polystyrenes, ethylene/propylene/diene rubbers, polyketones, ethylene/styrene copolymers, alpha-olefin/polar monomers copolymers, conjugated polymers, biodegradable polymers, photochromic polymers, electro and photoresponsive polymers, photoisomerisation, non linear optics, holography, optical filters, acrylic and fluoroacrylic polymers, fluorinated polymer blends.

A2:Status of the research in the field

Although Ziegler-Natta catalysis is not a mature polymerisation technology, new catalytic systems based on soluble metal complexes are emerging as a valid alternative exhibiting higher activity and selectivity as well as greater versatility. Among single-site metal catalysts, metallocenes are already an industrial reality, while the catalysts based on early and late transition metals with polydentate s-donor ligands, actinides or lanthanides are still at an early stage of research and development (apart from the production of polyketones with Pd diphosphine complexes).

With metallocene complexes, several polymers may be produced which are inaccesible to Ziegler-Natta catalysts, for example syndiotactic polystyrene, syndiotactic polypropylene, ethylene/styrene and ethylene/butadiene copolymers, polycycloolefins, and copolymers of ethylene and cyclic olefins. Improved metallocene structures must be designed, however, to solve a number of problems that still maintain metallocenes in semiscale application. For example, one of the major problems is the synthesis of supported metallocenes for application in existing polypropylene conventional plants, while metallocenes capable of effectively copolymerizing ethylene with polar monomers are still unknown.

The potential of f-block elements, in particular of lanthanides, is still largely unexplored. Given the fact that organolanthanides are among the most active homogeneous single-component catalysts and that they are the only systems capable of providing block copolymers of ethylene with polar monomer such as acrylates, methacrylates, and caprolactone, a systematic study of the organometallic chemistry of these elements towards novel polymerisation catalysts is warranted.

Preliminary studies of single-site non-metallocene catalysts show these compounds to have an even wider potential than metallocenes. The production of polyketones from CO and ethylene and propylene by palladium catalysis is already carried out at industrial level, but the search of new and more efficient catalysts is at present intensely pursued. New phase systems (water as solvent) or different metals (Ni) are being investigated. Efficient catalysts for the copolymerisation of CO and alpha-olefins, e. g. styrene or polar comonomers like methyl acrylate, are still unknown.

The largest applications of late transition metal catalysts are envisaged in the productions of polyethylenes (from HDPE to highly branched PE) (Ni, Pd), linear polyethylenes (Fe, Co), alpha-olefins/polar monomer copolymers (Pd, Ni), polycycloolefins (Pd), and oligomerisation to alpha-olefins (Fe). Unresolved problems of particular relevance can be singled out in the selective alpha-olefin oligomerisation (alternative to the Phillips chromium-based technology) and in the copolymerisation of ethylene and/or alpha-olefins with polar monomers, especially with maleic anhydride, maleates, acrylic amide, acrylonitrile, vinyl fluoride, allyl benzene, vinyl ethers, perflurobutylethylene, etc. Alpha-olefin oligomerisation catalysts based on early transition metals such as Cr might have a great margin of improvement.

Despite the successful use of Ziegler-type vanadium catalysts for the production of valuable and profitable EPDM, there is a dearth of rationally designed and well-characterised organovanadium catalysts. The complicated chemistry of vanadium complexes (paramagnetism, facile change of oxidation states) clearly points to the fact that more efforts have to be made to understand and exploit the organometallic chemistry of this metal. An important issue regards the toxicity of vanadium, which remains in the polymer as a residue (< 1ppm).

Ring-opening cross metathesis, and ring-opening metathesis polymerisation of cycloolefins offer a simple access to functional polymers containing C=C bonds suitable for mixed functionalisation or cross linking. The recent discovery of living ruthenium catalysts containing bulky ligands opens the route to more efficient systems, especially cationic ones, and to their use in the preparation of block copolymers.

The atom transfer radical polymerisation (ATRP), a 4-year old process, constitutes a tremendous technique for the development of controlled radical polymerisation leading to functional copolymers. The importance of radical polymerisation is related to the large variety of monomers, which can be polymerised and copolymerised in mild reaction conditions. However, the control over the macromolecular structure is poor and much lower as compared to ionic polymerisations. The possibility of controlling molecular weights, polydispersities and terminal functionalities via ATRP is thus extremely desirable. While radical living catalysts of ruthenium or copper have just been discovered, scrutiny of other metals and better understanding of the reaction mechanisms are needed for any further development.

Methods, methodologies and approaches which may be necessary for the preparation and evaluation of collections of compounds ("libraries for combinatorial chemistry") with potential as polymerisation catalysts with desired properties are virtually non-existent.

In conclusion, the status of the research in the field is such that an enormous amount of further work is apparently necessary to address the above mentioned and other problems related to the development of a new generation of single-site metal catalysts specifically tailored for the efficient oligomerisation, polymerisation and copolymerisation of saturated hydrocarbons as well as copolymerisation with various cheap feedstocks through more selective, less costly and more environmentally friendly procedures.

A3:Relationship with other European Programmes

There is no particular specific European programme devoted at present to polymerisation processes via metal catalysis except to the extent that COST Action D12 "Organic Transformations: Selective processes and asymmetric catalysis" may be complementary to this new Action. Optically active ligands are indeed required to produce new chiral catalysts giving appropriate polymer tacticity. It is expected that this COST-action will be relevant if not important to various other COST-actions. Examples include COST Action D14 " Functional molecular materials" and, especially COST Action D16 "Combinatorial chemistry". These Actions and other European initiatives in 5th framework program (BRITE, TMR) are likely to benefit from a COST Action "Oligomers, Polymers and Copolymers via Metal Catalysis".

B.OBJECTIVES OF THE ACTION AND SCIENTIFIC CONTENT

B1:Main objective

The main objective of the proposed COST Action is to gather chemists with complementary expertises in the areas of design of single-site polymerisation catalysts, heterogenisation of single-site catalysts, design of new polymeric materials, characterisation and processing of polymers and optimisation of manufacturing processes featured by minimal environmental impact.

For the back-translation of desired polymer properties to molecular properties of the polymer molecules, it will strongly be encouraged the collaboration between scientists from the polymer industry and academic polymer groups in order to rapidly determine whether new products have properties justifying further development and to get feed-back on what fundamental problems have to be solved to allow for the commercial exploitation of new polymeric materials.

As it is, this Action satisfies the general aims for a proposed cost action which may be summarized in the slogan: "Strengthening the competitiveness of Europe". Currently, there is indeed a strong competitition, at both the industrial and academic level, between Europe, the USA and Japan in the field of single-component polymerisation metal catalysis. Europe does not have the advantage of the United States of a couple of large granting agencies, but to a certain extent the EU can assume this role. Starting this COST action will promote cooperation between both academic and industrial scientists of the member states. By doing so, an inter-European exchange of post-docs will be stimulated encouraging the best European young researchers to spend a post-doctoral stay in Europe rather than in the United States.

Nearby future action: WEB-site page "Oligomers, Polymers and Copolymers via Metal Catalysis" as part of the page for COST-chemistry.

B2:Sub-Topics

1.Metallocenes
Synthesis, characterisation and catalytic performance of new metallocene catalyst precursors. General working methodology: design and synthesis of the catalysts; characterisation of the precursors in both the solid state and solution by means of standard analytical, spectroscopic (NMR, EPR, IR, UV-vis, MS, etc.) and X-ray diffraction techniques; heterogenisation of specific catalysts by grafting to solid inorganic and organic supports; study of the catalytic performances in situ (via high-pressure NMR and IR spectroscopies) and in actual high-pressure reactors; study of the interactions between metal centres and monomers and engineering of coordination catalysts so as to modulate catalyst actvity according to monomer reactivity; study of the relationships between the structure of the metallocene and the regio- and stereo-selectivity of the enchainment of the unsaturated substrates; study of cation-anion interactions; creation of a library of compounds for use in combinatorial chemistry.

2.Early and late transition metal complexes
Synthesis, characterisation and catalytic performances of new polymerisation catalyst precursors formed by early and late transition metal ions stabilized by polydentate ligands with N, O, S, P donor-atom sets. General working methodology: same as above. In addition, immobilization of the catalysts in aqueous phase (SAP catalysis).

3.Polymer characterisation
Macromolecules, like magnetic tapes, store information concerning the polymerisation process. This information which is of vital importance for the evaluation of the catalytic performance and for its improvement, is obtained by determining the following primary structure properties. In homopolymers: molecular weight, molecular weight distribution, end groups, stereoregularity type and distribution, branching. In copolymers: chemical composition, comonomer distribution.

Examples of specific topics that could be addressed in the Action

a)Living polymerisation and copolymerisation of ethylene and alpha-olefins and copolymerisation of alpha-olefins with functionalized monomers assisted by either metallocenes of early transition metals, lanthanides and actinides or late transition metal complexes with polydentate ligands (Fe, Co, Ni, Ru, Pd) (search of 1,2-insertion products).

Polymerisation of polar monomers to polymers of well-defined molecular weights, molecular weight distributions and tacticities (e. g. synthesis of tactic poly(methyl)acrylates, polynitriles, polyvinylacetates, etc).

Synthesis of polybutadiene via environmentally friendly procedures, e. g. applying lanthanide catalysts.

Synthesis of block copolymers of differently functionalized (polar) monomers and of polar-nonpolar monomers.

Synthesis of diblock-, triblock-, star-, comb-copolymers, ionomers and dendrimers.

Effective control of EPDM and of related copolymers.

Improve the production of EPDM elastomers by either activating the vanadium catalysts so as to reduce the metal concentration below 1 ppm in the polymer or use new metallocenes or other single-site catalysts (even in gas phase) to increase molecular weights and molecular weights distributions.

b)Oligomerisation of ethylene into linear a-olefins with Ni(II), Fe(II), Co(II) and Pd(II) complexes stabilized by ligands containing various donor atoms sets (P,N;P,O;O,O;As,O;S,S;N,N).

Search of selective and environmentally friendly processes. Design of a new generation of Cr-based oligomerisation catalysts.

c)Copolymerisation of CO and ethylene and/or a-olefins or cyclic olefins into polyketonic materials using Pd(II) or Ni(II) complexes stabilized by bidentate ligands with P,P, P,N or N,N donor atom sets in different phase-variation systems.

Explore the possibility to replace alpha-olefins with a polar comonomer such as methyl acrylate.

Study of the factors determining the relative stability of the two possible isomeric structures, the polyketone and the spiroketal one, to have access to a new class of "smart materials" changing from the carbonyl to the ether chromophore (or viceversa).

d)Ring-opening metathesis polymerisation of cyclic olefins (ROMP) with metal carbene and cumulene complexes containing chiral ligands or tolerating functional groups.

Design of cationic catalysts and study of the influence of counter-anions. Development of new, well-defined ROMP and ADMET catalysts for the living polymerisation of unstrained functiolaized cycloolefins. Search of new categories of ligands to extend the applications of known catalysts and to provide a better spatial control of the resulting polymers.

In-depth studies of the factors that influence the carbene-metallacyclobutane equilibrium and the stereochemical outcome of the reactions.

e)Atom transfer radical polymerisation (ATRP) promoted by living catalysts derivatives of late transition metals.

Paramagnetic metal complexes for radical polymerisation. Study of atom trapping to generate living radicals.

New initiators for ATRP. Radical copolymerisation of alkenes and polar monomers.

C.SCIENTIFIC PROGRAMME

The scientific programme will depend on the projects submitted by individual research teams. The working group projects will be selected according to the objectives outlined above.

At this stage there is no specific scientific programme suggested for this action in order to place no limitations on the invited proposals. The selection will strictly occur according to the outlined objectives.

D.ORGANISATION AND TIMETABLE

D1:Organisation
Research projects fitting in the subtopics described in section C will be submitted by scientists to the Management Committee members. This Committee will establish contacts between scientists.

The Management Committee has responsibilities for:

1.Drawing up the inventory during the first year, organisation of workshops and start of the activity; existing contacts will be used which should greatly facilitate this task.
2.The co-ordination of the joint activities with other COST Actions; joint meetings are likely to result from this activity.
3.Exploration of wider participation and exchange of information with EC specific programmes, ESF, etc.
4.The planning of the intermediate report, the final report and the concluding symposium.
Progress in each of the projects will also be reported by the respective participants in their own countries within the framework of existing programmes.

D2:Reports

The progress of the programme will be monitored by brief annual reports from each of the participating scientists which will describe the results of research obtained through concertation. A milestone report will be prepared by the Management Committee after 2 years of joint activities. The report will be presented to the COST Technical Committee for Chemistry for their review.

A final report will be published to inform nonparticipating scientists and research workers interested in the results about the scientific achievements of the Action. It is expected that some reviews by participants which describe the progress made and state of the field will be published in International Journals. To conclude the COST Action, a symposium will be held after 5 years which will be accessible to other scientists.

D3:Timetable

The Action will last five years and comprise the following four stages:

Stage 1:After the first meeting of the Management Committee, a detailed inventory of ongoing research and existing plans of the participating groups to begin joint projects will be made. This will result in a discussion document which will allow further planning to occur.

Stage 2:It will be evident which projects are closely related and would benefit from joint activities. Researchers (and coworkers) will set up (and continue) joint collaborative projects and exchange their recent research results. It may be appropriate to explore wider collaboration with other European countries during this stage.

Stage 3:An intermediate progress report will be prepared after 2 years for review by the COST Technical Committee for Chemistry and by the COST Senior Officials Committee.

Stage 4:This final phase will begin after 4 years and will involve the evaluation of the results obtained. It may include the organisation of a symposium for all the participants and co-workers.

E.ECONOMIC DIMENSIONS

The economic dimension of the Action (initial estimate of total costs = personnel + operational + running + commission costs) is: EURO 120 million.

The human effort in the area of "Oligomers, Polymers and Copolymers via Metal Catalysis", as described in this document, amounts to 1 000 man-years (200 researchers during 5 years), being equivalent to EURO 100 million approximately.

E1:Personnel costs

Estimates of personnel costs (research + administration) will depend on the rates applicable for various EU countries (one man-year = EURO 100 k).

Estimates of personnel costs (research + administration) are as follows:

Sub-topic 1: in about 20 countries a total of 400 man-years, totalling EURO 40 million

Sub-topic 2:in about 20 countries a total of 400 man-year, totalling EURO 40 million

Sub-topic 3:in about 20 countries a total of 200 man-years, totalling EURO 20 million

E2:Operational and running costs

The estimate of the total operational and running costs including costs of instruments and materials is EURO 20 million.

E3:Co-ordination costs

The costs of co-ordination to be covered by the COST budget are estimated to be EURO 120 k per year, i.e. a total of EURO 600 k for the five years duration of the project. (i.e. 0.5% of the total cost of the research coordinated).

F.DISSEMINATION OF SCIENTIFIC RESULTS.

All publications arising from research carried out under COST Action D17 will credit COST support and the Management Committee will encourage and promote all co-authored papers. Results of research carried out by the working groups under COST Action D17 will be submitted to international scientific journals and reviews.

Joint meetings among different working groups in COST Action D17 and with working groups from other COST Actions, particularly with those of COST Actions D14 and D16, will be organised in such a way as to best promote interdisciplinary communication.

The Management Committee (MC), in conjunction with the working groups (WG) of the Action, will meet one meeting every year with the main aim of presenting results to the MC as a whole and, where possible, the MC will invite potential users and interested parties to this meeting.

The Management Committee will, during the first year of the Action, also set up a workplan for interdisciplinary events for the dissemination of results of the COST Action D17.

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