IK4-CIDETEC Researchers Develop Room-temperature Self-repairing Elastomers

Researchers at IK4-CIDETEC have created a polymer capable of self-repairing at room temperature without the need of any catalysts or any external stimulus. After being cut in half, the material is able to regenerate itself in just two hours, fully recovering its mechanical properties.

This new polymer is based on a poly(urea-urethane) type composition, a material which is widely used in industry. Therefore, and because it can be easily scaled-up, this new development is expected to reach the markets shortly. Its discovery opens a wide range of industrial applications in the use plastic components, in both electrical and automotive sectors, as well as in construction and in the development of biomaterials.

Triggers to promote bond repair include energy inputs, such as heat or light, or specific environmental conditions, such as pH. Self-healing polymers that can spontaneously achieve quantitative healing in the absence of a catalyst have never been reported before, until now.

Ibon Odriozola previously came close when his group at the CIDETEC Center for Electrochemical Technologies in Spain developed self-healing silicone elastomers using silver nanoparticles as cross-linkers. Unfortunately, an applied external pressure was required and the expensive silver component disfavored commercialization. But now they have achieved their goal to prepare self-healing elastomers from common polymeric starting materials using a simple and inexpensive approach.

An industrially familiar, permanently cross-linked poly(urea-urethane) elastomeric network was demonstrated to completely mend itself after being cut in two by a razor blade. It is the metathesis reaction of aromatic disulphides, which naturally exchange at room temperature, which causes regeneration.

Ibon stresses the use of commercially available materials is important for industrial applications. He says the polymer behaves as if it was alive, always healing itself and has dubbed it a "terminator" polymer - a tribute to the shape-shifting, molten T-1000 terminator robot from the Terminator 2 film. It acts as a velcro-like sealant or adhesive, displaying an impressive 97% healing efficiency in just two hours and does not break when stretched manually.