Self-healing materials are exactly just what you thought them to be: composite, synthetic materials that are designed to repair itself (to a degree) when subjected to various forms of damaging stress. Its modern iteration was first conceptualized by the early 2000’s, and the research still continues today to include more ideas, techniques, and disciplines.
For the researchers at Harvard SEAS, the field now also includes their latest growing research: a new rubber material that can mend itself back into shape using a new binding method.
The Rope that Ties Polymers
Another research from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) is this time trying to research a new method to make self-healing rubber. The ‘trick’ that they have come up with, is that instead of focusing on rubber’s intrinsic properties, they instead focused on building on its formed bonds.
As explained by the report, rubber’s strength comes from its molecular covalent bonds. Its polymers are connected via these permanent hardened connections. This is the reason why your car’s tires can take all forms of punishment for quite a while before ever needing to stop at the vulcanizing shop. The catch however, is that despite its strength, once it does get damaged, the bonds cannot be easily reconnected again, at least without using special manufacturing treatments.
For the current research, the scientists developed a “molecular rope”, designed to tie the hard covalent bonds to the not-so-hard-but-repairable hydrogen-based bonds. This forms what they called as a randomly branched polymer. With both hard and soft polymers mixed evenly throughout the transparent material, it forms a homogenous, balanced mix between hardness and repairability.
When subjected to considerable stress, the material eventually forms fibrous cracks on the material. Unlike cracks on ordinary rubber however, the damage is often redistributed properly around the material, so that no point would actually tear. When there is no stress applied, the cracks slowly disappear, healing the material’s damage over time.
Spare Tires Begone
The report gave considerable mention to the previously developed “soft rubber”, which, although was capable of self-healing, was nowhere as tough and sturdy as its industrial counterpart. There have even been a number of research endeavors regarding self-healing rubber throughout the decades. However, this is the first time that a method was ever devised that actually made use of ordinary rubber.
Why is this important? The use of ordinary rubber in the developed hybrid material could indicate the creation of a bridging cost-effective material. Since a brand new material would take time before it gets optimized for industrial use, utilizing already available materials can lower the initial cost of the technology. So long as it gets developed over time, the gradual shift would then eventually make the technology better and better. Soon, it could even abolish the use of regular rubber altogether.
The current objective of the research is to understand further the inner workings of the material’s damage-inducing mechanisms. This way, they would have a better picture of its functions, and thus, provide a clearer picture of its potential uses in the future.
Source: Harvard SEAS