In a typical factory, manufacturers convert raw materials into finished products; but their duties are tempered by a discomfort: the aging of materials.

Aging will directly influence the performance of a specific material—and when its initial properties are irreversibly changed, the given material is rightly classified as functionally obsolete.

The same cannot be said about self-healing materials.

Author Teodora Gaici | Copperberg

Each material used in a facility is bound to get fractured under external stimuli, such as temperature, light, moisture, or chemical agents.

At times, this damage is reversible.

From rubber to metals and polymers, all the materials with self-healing properties can fix themselves and spontaneously enrich their longevity without human intervention.

It may seem like an unfathomable undertaking, but a self-healing mechanism that repairs its fractures—autonomously or through external stimulus activation—is not a novelty; far from it. This built-in ability to recover functionality after material degradation, damage, and failure was proposed in the 1980s.

The mechanism has been fully developed in the early 2000s and collective sentiment about next-generation materials has been on the rise ever since.

A Gnomic Material That Lives On

As industry players put the bulk of their efforts into extending the lifespan of material-intensive products, they started crafting a class of synthetic substances that mimic the autonomic healing abilities of biological organisms.

How do these synthetically-created substances work? The self-healing functionality of a polymer, for example, is heavily contingent on three mechanisms:

  • Embedded Healing Agents. The addition of microcapsules—or more precisely, healing agents—into the material matrix in order to instantly seal up the crack.
  • Microvascular Networks. The introduction of a microvascular network that flows throughout the material to swiftly pump the healing agents into the affected area.
  • Intrinsic Systems. The incorporation of a dynamic bonding character into the polymer—a process needed to alter the molecular structure of the polymer for endowing this material with self-healing property.

A material that intrinsically heals itself can repeatedly recover its properties. As it routinely repairs molecular and macroscale damages, an intrinsic self-healing polymer allows multiple healing steps in the same location.

Conversely, extrinsic self-healing polymers that incorporate encapsulated precursors perform a single-time operation and therefore, multiple healing is not possible. If the damage occurs again at the previously healed area, the extrinsic mechanism can’t achieve a high healing efficiency level and is prone to failure.

Sometimes, in spite of all evidence to the contrary, opposites do have something in common: both intrinsic and extrinsic self-healing materials may not have to be replaced—and with that, a set of remarkable benefits are coming into focus. Industry experts reveal that self-repairing materials could promptly:

  • Prevent costs incurred by material failure
  • Lengthen product lifetime while increasing safety and reliability
  • Lower production costs by reducing maintenance requirements

The conventional healing process of a particular structure is costly and time-consuming, as it should also be assisted by expert technicians.

Materials with a built-in autonomic healing capability are mimicking living tissues and, by contrast, they can automatically restore their structural integrity while reducing the subsequent probability of failure. What is really remarkable, though, is that human intervention is not mandatory in this case.

That is, of course, until an impasse is reached: the great majority of self-healing materials deliberately rely on a set of chemical mechanisms. In consequence, external stimuli (e.g. heat or pressure) prompt them to heal. Chemical networks, however, are hindered by water, acid, or alkaline solutions—a group of limiting factors that will thwart self-healing.

Is this a reasonable risk for professionals to take? Organizations may soon have an answer. Now, as the global self-healing materials market is projected to reach USD 2,447.7 million by 2021, the industry is imposing stringent regulations on structural integrity in hopes to eliminate potential restraints.

The Rush Towards Future-Proof Healing Materials

In a notable effort to come to grips with a novel ability for damage healing, professionals are running up against a hard reality: what is to be done about the limitations of self-healing materials?

It’s relatively early to be speculating about irreversible barriers or the ground-breaking innovations that can indisputably halt risk. But that’s not to say upheavals aren’t an immediate possibility.

Industry professionals won’t merely observe and stay in the background. As challenges abound, industry experts are taking swift action to prevent the nadir of self-healing limitations and, as a result, provide instructive examples of next-generation materials.

A new class of smart materials is “formed by the copolymerization of ethylene and anisyl-substituted propylenes,” scientists note. The unique mechanical properties allow materials to autonomously self-heal—and reportedly, they do “not only [heal] in a dry environment but also in water and aqueous acid [or] alkaline solutions, without the need for any external energy or stimulus.”

Progress is being made. For now, Self-Healing UI is another testament to this fact. A group of researchers recently developed this “soft-bodied interface that can intrinsically self-heal damages, reconfigure, and fuse.” All this is made possible without external stimuli—the primary limiting factor of self-healing efficiency.

Any interface with the sensing capability of Self-Healing UI will promptly “detect when it is cut into halves or joined together,” researchers explain, “[and] it can heal completely in a matter of 6 hours.”

While Self-Healing UI is still in the testing and development phase, manufacturers can shift their attention to intelligent soft robotic systems. If a self-healing mechanism can enrich the durability, mechanical robustness, and longevity of soft-matter machines, it will undoubtedly break the mold in the field of manufacturing.

When the soft-matter technology enters a real-world environment, the self-healing mechanism allows it to withstand stretching, bending, twisting as well as scrapes, cuts, and punctures. Such functionality, as specialists say, requires materials with embodied intelligence to self-diagnose and detect damage.

A next step might be analyzing the material’s performance using AI—a technology that can putatively identify change in the underlying material microstructure and accelerate device performance.

Shielding Against Damage, Decay, and Permanent Failure

Material immunity—that’s arguably the bellwether of innovation in the manufacturing field.

There may be very few companies producing self-healing materials at the moment; and yes, they are more expensive than conventional materials.

But to some extent, the increasing demand for self-healing materials is evidence that growth, and implicitly innovation, is surging ahead.

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