Coordination Chemistry Inspired Advances in Controlled Radical Polymerisation

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Chemistry

Abstract

Polymers are ubiquitous materials that have touched every aspect of our lives. These inexpensive, varied macromolecules are particularly impressive due to the diversity of physical properties and applications accessible. Innovations ranging from commodity materials to smart coatings to nano medicine are built from the foundation of polymer chemistry. This is especially important in the UK, where the polymer industry contributes >2% of UK GDP.

The tools that polymer scientists and engineers use are also growing. In particular, control over both polymer macrostructure and microstructure has seen an explosion in research activity, particularly in the field of Controlled Radical Polymerisation (CRP) which offers scientists the chance to reproducibly control the synthesis of individual macromolecules. This is achieved through several strategies, but arguably none are as robust as atom transfer radical polymerisation (ATRP). This process has transformed the polymer industry and accessed polymer morphologies and structures with tunable properties, self-assembly, applications and structures. Challenges remain, however, in examining systems beyond copper catalysts. In particular, non-toxic initiators that de-colour readily and are easily tuned are an important target, especially in producing plastics and coatings for packaging and biomedical applications.

Building from our expertise in iron-based systems for CRP, we propose to investigate Fe and Ti based catalysts. Our strategy is unique in that it is inspired by an understanding of coordination chemistry. Through this research programme we will develop new catalysts, with innovation in ligand design and catalyst development; develop new protocols to quickly screen and assess catalyst performance; develop a novel strategy to introduce secondary tuning into the coordination sphere to shape complex reactivity; significantly expand the monomer scope of Fe-mediated CRP; develop new applications at the interface between ethylene/functional monomer polymerisations and vinyl acetate branching.

Through these activities we will establish our iron and titanium systems as the preferred technologies for CRP processes, developing a system that is both environmentally and financially sustainable. Expanding from basic commodity polymers to specialty applications and polymers will diversify the UK product base whilst increasing sales. We will strengthen the UK expertise in CRP to new green ATRP catalysts, promoting innovation whilst minimising environmental impact.

Planned Impact

Who will benefit from this research?
(1) The global polymer industry, particularly in the UK
(2) Government, public and industrial bodies targeting carbon dioxide reductions
(3) Residents of the UK, the EU and abroad
(4) The polymer academic community

How will they benefit from this research?
(1) The UK polymer industry employs nearly 290,000 people and has annual sales worth over 2% of UK GDP. These materials are predominantly derived from petroleum resources, with a particular focus on the preparation of high volume commodity polymers with narrow profit margins. With the fluctionality in oil prices providing instability in polymer markets, diversification is essential for continued economic growth in the polymer sector. This research proposal will provide increased value from existing supply chains whilst also opening up new product sectors within the specialty polymer industry. The polymer industry is a supplier to a vast range of other industries in the UK and abroad. Applications in the packaging, transportation, medical, electrical and manufacturing sectors expand the impact of this research significantly. Our catalyst development work has the opportunity to directly impact this industry: We have shown strength in catalyst commercialisation - our first generation iron systems will be sold by Aldrich and several companies are testing our catalysts in pilot facilities through GreenCentre Canada. We believe our second generation catalysts offer an improved approach, producing alternatives that are both inherently flexible, easy to tune, and broad in scope.
(2) While there are clear economic factors as drivers for sustainable change, the environmental impact of polymers on our community needs to be addressed by passionate policy-makers, environmental groups and chemical organisations. A key message to policy makers, especially with the growing strength of the UK's petroleum industry, is that environmental progress and sustainability does not need to depend solely on renewable plresources, but rather the efficient use of all available resources. Policy-makers can focus on sustainability and efficiency as target goals. A key metric in the growing concern over sustainability is carbon dioxide emissions. Our system design will minimise purification solvents: white polymers are accessed by simply acidifying the solutions which can then be semi-batch processed or precipitated. In our previous work we have reduced solvent use by 90% over a traditional copper catalyst, drastically reducing waste, lowering carbon dioxide emissions and improving sustainability. By proving the utility of these complexes on a UK scale it is expected that IP may be out-licensed to the larger EU polymer community and to global partners to further increase the impact of the research.
(3) Residents of the UK, EU and abroad will benefit three-fold from the development of this research proposal: (i) Less waste, less toxicity and improved sustainability for the production of specialty plastics will lead to safer products and reduced incinerator waste and thus lower carbon dioxide emissions. (ii) The jobs in the polymer, petroleum and manufacturing sectors that drive our economy will be more secure, and in fact will likely expand through commercialisation of these complexes and the products we can prepare. (iii) New products, new plastics and new materials with improved properties and new-to-the-world applications will be developed, providing advances in our livelihoods.
(4) The research within the polymer academic community will also have a far-reaching effect. The staff trained within this
programme will be able to transfer their skills and expertise across the UK, increasing productivity, disruptive thought and
translational knowledge in numerous sectors. We also hope that our strategy for CCI-CRP is inspirational, encouraging other academic breakthroughs in the UK and beyond.

Publications

10 25 50
 
Description We have discovered and developed the interplay between two key mechanisms of controlling radical polymerisations. More specifically, we have shown that both halogen mediated and organometallic mediated pathways are accessible by the same system. We have used this knowledge to design new systems that are capable of controlling polymerisations through an entirely organometallic pathway and isolated key Fe(II) and Fe(III)R intermediates.

More recently we have discovered a new class of Ti(III) complexes capable of controlling (meth)acrylate polymerisations under similar conditions. We can show that the mechanism (hypothesised by previous groups to be radical) is likely coordination insertion - and that the system shows remarkable control. We have now discovered that the reaction undergoes a unique group transfer polymerisation - a bimetallic mechanism where a Ti(IV)-enolate is shuttling with a Ti(III)-MMA adduct. This unique work has been submitted for publication.
Exploitation Route We are collaborating with polymer scientists and potential industry partners to see whether our systems could be exploited commercially, as described elsewhere. We are disclosing this new Ti(III)/Ti(IV) bimetallic mechanism which may impact the development of earth abundant catalysis.
Sectors Chemicals,Manufacturing, including Industrial Biotechology,Other

 
Description Cryo-FIB-SEM-CT: a 'three-in-one' imaging facility for opaque soft matter
Amount £1,313,346 (GBP)
Funding ID EP/P030564/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2017 
End 03/2018
 
Description Polymeric Frustrated Lewis Pairs
Amount £321,264 (GBP)
Funding ID RPG-2019-019 
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2019 
End 10/2022
 
Description Soft Matter and Functional Interfaces CDT
Amount £100,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 05/2016 
End 08/2019
 
Description Nagoya University / Chubu University 
Organisation Nagoya University
Country Japan 
Sector Academic/University 
PI Contribution Collaborations on the mechanisms of radical polymerisations with Profs. Shige Yamaguchi (Nagoya, organoboron radical traps) and Mitsuo Sawamoto (Chubu, metal radical traps, stereo-regular radical reactions) in Aichi Prefecture in Japan. We have discussed mechanism, assisted with data interpretation and screened complexes as degenerative-transfer catalysts in CRP for the teams.
Collaborator Contribution The partners provided samples for us to test, and advice on product handling. They provided expertise on synthesis and mechanism.
Impact No outputs to date.
Start Year 2017
 
Description Synthomer 
Organisation Synthomer plc
Country United Kingdom 
Sector Private 
PI Contribution We are working with Synthomer to evaluate polymerisation mechanisms, processes and products for commercial applications. This includes presentation of results, discussion of polymer product application scope, preparation of samples and a planned 3 month research visit for a PhD student in their UK research laboratory.
Collaborator Contribution Synthomer has provided project leadership from three senior scientists, evaluating catalysts and processes in both existing systems and emerging markets. They will host a 3 month research visit for a PhD student in the next 12 months.
Impact Outcomes have shown that Fe-based systems likely have less potential than undisclosed new Ti-based systems that are focus of current research efforts.
Start Year 2015
 
Description University of Goettingen 
Organisation University of Göttingen
Country Germany 
Sector Academic/University 
PI Contribution We collaborated on understanding iron mediated controlled radical polymerisation via EPR, Mossbauer and in-situ kinetic experiments. We synthesised and provided all Fe(III) and Fe(II) catalysts used.
Collaborator Contribution The partners ran the preponderance of spectra and assisted with analysis of data.
Impact Two manuscripts coauthored with the principal collaborator, Prof. Michael Buback.
Start Year 2014
 
Description University of Toulouse 
Organisation University of Toulouse
Country France 
Sector Academic/University 
PI Contribution We outlined challenges in understanding, from a computational chemistry perspective, the interplay between organometallic and halogen transfer pathways in iron mediated controlled radical polymerisation.
Collaborator Contribution Led by Prof. Rinaldo Poli the group performed density functional theory level calculations that assisted in understanding the mechanism of these important reactions.
Impact Two manuscripts coauthored with Rinaldo Poli published in Inorganic Chemistry and Chemistry - A European Journal.
Start Year 2014
 
Description Biodesign Challenge 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact A talk and interactive session with students interested in BioDesign - discussing the nature of plastics processing, sustainable catalysts, and macromolecular structures and sustainability.
Year(s) Of Engagement Activity 2017
 
Description Cabaret of Dangerous Ideas 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Show at the Edinburgh Fringe Festival on sustainability in plastics, including coverage of research outcomes of this specific grant. Audience was general public - with members from an international reach, as lots of tourists inspired to see this particular show whilst visiting Edinburgh.
Year(s) Of Engagement Activity 2016
 
Description FameLab 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Lead Judge for Scottish Final of FameLab. Discussed our research and put other research into global context.
Year(s) Of Engagement Activity 2015
 
Description Schools talks in Mumbai 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Visited 3 schools in Mumbai, India and presented lecture on green chemistry and green materials. Approximately 100 students total attended the lectures.
Year(s) Of Engagement Activity 2015
 
Description Sustainable Artists Collaboration / Royal Botanical Gardens 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact Working with ceramicists and fibre artists on improving sustainability in their artwork through use of sustainable plastics and polymers. Integrating materials from Royal Botanical Garden into research.
Year(s) Of Engagement Activity 2017,2018