Smart polymers for prosthetics and sensors
Compounds consisting of repeated units (polymers) are everywhere, from naturally occurring ones such as DNA and cellulose to synthetic varieties, in particular plastics. Electromechanical materials are adaptive or smart materials that (reversibly) respond to electrical fields with mechanical changes in parameters such as strength, shape or elasticity. On a macroscale, their potential for use in prosthetics is clear – electrical impulses from nerves could cause changes in synthetic muscle. On a microscale, individual polymer molecules respond to an applied electric field with changes in conformation, facilitating development of micro-sensing devices. Novel electromechanical polymers were the focus of study for the ‘Mechanically interlocked actuating conjugated polymers’ (MIA-CP) project. In particular, scientists sought to introduce mechanically (rather than chemically) bonded architectures to conducting materials with a focus on prosthetics, sensors and other devices. MIA-CP project partners synthesised a completely new material comprised of molecule-sized hoops (pendant macrocycles) hooked together and locked in place. Not only is it an excellent candidate for synthetic muscle due to its flexible cross-linked structure, but it could also be the first step to novel sensors given its ability to trace acid vapour via changes in electric current. Additional published work described the synthesis of another conjugated polymer with potential for use as an artificial muscle. Conjugated carbon polymers were also produced via novel methodology enabling bonding of macrocycles to carbon nanotubes. Such materials could open the door to innovative electroactive devices in the future. The MIA-CP project successfully combined state-of-the-art mechanical bonding technologies with recent advances in conjugated polymer synthesis to produce a new generation of high performance electromechanical materials. The synthesised polymers have important potential for use in artificial muscles, sensors and other electrochemical devices. Given that so-called smart materials are designed based on nature, perhaps using them to replace natural mechanisms that have failed is a natural choice.
