NSF: Healing polymers: A self-assembly approach

Lead Research Organisation: University of Reading
Department Name: Chemistry

Abstract

The creation of new polymeric materials is the focus of synthetic organic polymer chemists. The synthetic routes employed normally by polymer chemists to generate high molecular weight polymeric materials involves coupling together low molecular weight materials that are referred to as 'monomers' via chemical bond formation processes. The resultant polymeric materials are used in all aspects of modern life, ranging from paints to lightweight aerospace components. Polymeric materials are exposed consistently to a wide range of environmental stresses, including chemical, electromagnetic, mechanical and thermal processes, that result in the degradation of material properties / polymer fatigue is a significant problem in structural and coating materials. Fatigue in plastics occurs commonly as a result of the formation and propagation of cracks, which can occur as a consequence of continuous or cyclic stress on the material. It has been proposed that this process starts at the microscopic level with formation of microvoids, which appear as a result of repeated mechanical stress on the material. These microvoids expand and combine into microcracks that lead subsequently to the onset of macroscopic crack formation and ultimate failure of the material. Conventional crack healing of a fractured polymer can be achieved by either heating the polymer, treating it with solvents or simple filling in the cracks. However, it is observed commonly that the repaired material does not offer the original strength or properties.Numerous weak interactions between polymer molecules play an important role in determining the properties of a polymeric material. However, only in recent times have these weak interactions been used specifically to create new materials. The term 'supramolecular polymer' has been used to describe materials of this type. Nature utilises weak intermolecular interactions extensively to create precise polymeric arrays - biopolymers such as DNA and proteins are notable examples of supramolecular polymer. 'Supramolecular polymerization' describes a process in which monomers assemble via the use of numerous weak interactions to generate a stable physically robust polymeric aggregate (an analogous process is the construction of large toy structures from small Lego(registered trademark) building blocks). From a mechanical point of view what makes supramolecular polymers different from more conventional polymer materials is their dynamic nature and thus they possess unusual thermomechanical properties.As part of a fundamental conceptual study, we propose to use multiple weak intermolecular interactions to assemble monomers units into reversible network-type polymers and investigate their potential as thermally-healable materials. This application of supramolecular polymerization processes will enable materials with higher stiffness and strength to be developed, while retaining the ability of the material to self-repair. While the primary target of the proposal is to create a new class of thermally-healable polymers , it is envisaged that this work will also lead to materials which possess very low melt viscosities, so opening the door to easier and cheaper processing (especially for long-fibre composite processing or surface coating technologies) and to the formulation of thermally responsive adhesives.

Publications

10 25 50
 
Description Supramolecular materials comprising blends of pyrenyl-end-capped polymers intercalating with chain-folding polyimides show near-quantitative thermal healability. Optimization of the supramolecular binding motifs enables tuning of toughness and healability. These materials exhibit greatly enhanced properties relative to systems in which the pyrenyl end-groups are replaced with weaker pi-stacking units, reflecting the different association constants between the complementary binding motifs.
Exploitation Route Polymeric materials underpin almost every aspect of modern technology, from electronic engineering to information technologies, textile and technical fibres, surface-coatings and, increasingly, composite structures for automotive and aerospace applications. However, continuous exposure of polymers to environmental attack through abrasion, impact, and mechanical or thermal stress can lead to degradation of physical properties and ultimately to irreversible damage and failure of the structure. The self-healing polymer systems developed in this project could lead to greatly enhanced damage-resistance and increased service-life for a wide range of structural and engineering components.
Sectors Aerospace, Defence and Marine,Chemicals,Construction,Electronics,Environment,Manufacturing, including Industrial Biotechology,Transport

URL http://www.soci.org/Chemistry-and-Industry/CnI-Data/2011/12/Polymers-with-healing-power
 
Description On the basis of Platform-researcher Greenland's pioneering work in self-repairing supramolecular polymer blends, Hayes and Colquhoun developed a collaboration with Domino Printing Sciences, of Cambridge to explore supramolecular polymer chemistry in the context of inket-printing applications (EPSRC Industrial CASE), resulting in very recent priority patent filings in this completely novel area. Domino have now (2016) funded a new PhD studentship at Reading in the same field, with co-funding from the EPSRC DTP. The grant also led to a new collaboration with Gnosys Global who funded a PhD studentship (from 2014) for work on self-healing polymeric cable-coating materials.
First Year Of Impact 2013
Sector Chemicals,Digital/Communication/Information Technologies (including Software),Electronics,Manufacturing, including Industrial Biotechology
Impact Types Economic

 
Description Collaborative PhD studentship: Healable polymers in power distribution networks
Amount £40,000 (GBP)
Organisation Gnosys Global 
Sector Private
Country United Kingdom
Start 01/2014 
End 12/2016
 
Description Collaborative PhD studentship: High strength supramolecular polymers
Amount £40,000 (GBP)
Organisation Atomic Weapons Establishment 
Sector Private
Country United Kingdom
Start 10/2010 
End 03/2014
 
Description Direct Industrial funding
Amount £85,000 (GBP)
Organisation BAE Systems 
Sector Private
Country United Kingdom
Start 10/2012 
End 09/2015
 
Description EPSRC Jumpstart grant
Amount £62,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2014 
End 12/2014
 
Description Healable composites
Amount £60,000 (GBP)
Organisation Cytec Industries 
Sector Private
Country United States
Start 01/2013 
End 12/2015
 
Description Platform Grant - Nanostructured Polymeric Materials
Amount £1,082,655 (GBP)
Funding ID EP/G026203/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 01/2009 
End 12/2013
 
Description Platform Grant Renewal: Nanostructured Polymers for Healthcare
Amount £1,185,824 (GBP)
Funding ID EP/L020599/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 06/2014 
End 05/2019
 
Description Supramolecular polymers for ink-jet printing
Amount £88,000 (GBP)
Funding ID IC/10002591 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 10/2010 
End 03/2014
 
Description Case Western Reserve University 
Organisation Case Western Reserve University
Country United States 
Sector Academic/University 
Start Year 2006
 
Description Domino 
Organisation Domino (UK)
Country United Kingdom 
Sector Private 
PI Contribution Industrial CASE award (EPSRC). PhD student developed new supramolecular polymers for application in industrial inkjet printing.
Collaborator Contribution Domino provided facilities for evaluating the new materials under actual inject printing conditions, including accommodation and travel for the PhD student working at Domino.
Impact Further PhD funding (2015-2017) following the success of the Industrial Case project. Patent filings by Domino in this field.
Start Year 2010
 
Description University of Delaware 
Organisation University of Delaware
Country United States 
Sector Academic/University 
Start Year 2006
 
Title Inkjet composition 
Description A printed deposit comprising a self-assembled supramolecular polymer formed by pi - pi stacking interactions between at least a portion of a first polymer (preferably an electron-rich chromophore comprising an aromatic or heteroaromatic ring, such as pyrenyl or naphthyl) and at least a portion of a second polymer (preferably an electron-deficient chromophore comprising an alkene or an aromatic or heteroaromatic moiety, such as a naphthalene diimide or a dinitrofluorenone). 
IP Reference GB2511623 
Protection Patent application published
Year Protection Granted 2014
Licensed Commercial In Confidence
Impact Impact on development programme of Domino Printing Sciences Ltd (Cambridge UK).
 
Description Self-Assembled Polymers: Recognition Motifs and Applications 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Invited lecture at the Department of Chemical Engineering, University of Colorado, Boulder, USA, June 2009.

Interest and questions afterwards.
Year(s) Of Engagement Activity 2009