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Highlights in Chemical Science

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Self-healing polymers prolong lubricant lifetime

28 January 2010

UK scientists have created self-healing polymers that could extend the lifetime of oils. These polymers are suitable to add to lubricants and could maintain the physical properties of oils for longer, they claim. 

Polymers are often added to oils to alter the physical properties such as viscosity; however, mechanical stress can break them, changing the properties they were added to create. Now a team of scientists led by David Haddleton, University of Warwick, UK have designed a self-healing, star-shaped polymer for use as a viscosity modifier.

Star-shaped polymers

Star-shaped polymers can repair their arms using a Diels-Alder reaction

The methyl methacrylate polymer has long arms which can get sheared off, so the team added Diels Alder adducts into the polymer backbone which allow them to reform via a Diels Alder cycloaddition reaction. 'Other types of chemistry such as free radical chemistry often undergo unwanted side reactions whereas the Diels Alder groups usually do only the Diels Alder reaction,' explains Haddleton. This selectivity makes the Diels Alder reaction particularly suitable for the reforming reaction in self-healing polymers where it's important to have very high conversions under mild conditions to minimise the loss in the polymer's performance. 

Stephen Craig, who investigates self-healing polymers at Duke University, US, comments that 'the field of self-healing materials represents a vibrant and promising research area, and truly molecular perspectives on material design and optimization as reported here, is likely to be critical as the field advances.'

The team now plan to 'optimise the chemistry before passing it on to our industrial collaborators, Lubrizol, for development in automotive lubricant applications,' says Haddleton. 

Russell Johnson

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Link to journal article

Self-healing polymers prepared via living radical polymerisation
Jay A. Syrett, Giuseppe Mantovani, William R. S. Barton, David Price and David M. Haddleton, Polym. Chem., 2010, 1, 102
DOI: 10.1039/b9py00316a

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