Self-healing materials take cue from nature

Various approaches have been implemented to develop self-healing materials, such as incorporating micro-capsules that break under stress and release the healing agent.  These approaches involve a tradeoff: increasing the amount of healing agent can weaken the structure of the material itself.

Researchers led by Prof Nancy Sottos at the University of Illinois Urbana-Champaign have developed plastics containing networks of channels that are less than 100 microns (0.1 mm), similar to a circulation system.  The channels are creating by incorporating "3-D scaffolds of 'sacrificial fibres' that mould the network of channels within a synthetic material, that are then destroyed in the final stage of production."  

Parallel channels can be used to separate resins from hardeners.  To speed up the flow, a circulatory system was creating using external syringes to keep the healing agents under pressure.  Alternative pulses of resin and hardener proved to be the most effective and have filled cracks up to a millimeter in size, 10 to 20 times larger than what can be achieved through micro-capsules.  The team is working on incorporating the pumps into the materials and exploring how to scale up their designs for real-world applications.

The team published Pressurized vascular systems for self-healing materials in the Journal of the Royal Society Interface.

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