Coatings & Polymers
Self-Healing materials have been a hot topic in materials science over the past few years. Here you can learn all about Self-Healing materials and how they function, find out more about the latest technological and commercial developments, and get inspired about the smart solutions that Self-Healing materials can offer.
Whether it is your smartphone, your brand-new coffee table, your car bumper or even the blade of a wind turbine, damage is almost inevitable and often strikes at the wrong moment. To make things worse, repair and maintenance methods are time consuming and costly, especially if the part is hard to access or expensive. The lifetime of our products can sometimes feel a little too short.
Not only can this be extremely inconvenient and expensive, but improved product lifetime is also becoming increasingly crucial for sustainable product design - creating products that last longer before being repaired or replaced. Using tougher, more resilient materials is one method to increase durability. This often comes at increased costs and these materials are still affected by damage and eventually fail. By continuously healing damage that may occur, Self-Healing materials offer an alternative, cost effective approach to product lifetime extension.
What are Self-Healing materials?
Self-Healing materials are, quite simply put, materials that have the ability to heal themselves. Since the early 2000’s, researchers have begun to use a number of innovative scientific techniques to create a range of materials that heal damage without any external input or activator.
This sounds like a very futuristic concept, but the first generation of these materials have been introduced to market. Self-Healing films for cars and mobile phone screens are already commercially available. These Self-Healing materials often have one shot at healing, require heat to repair, or only have the ability to repair minor surface scratches. Self-Healing concrete and Self-Healing asphalt for roads have also been developed!
Learn More!
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Self-Healing Microcapsules by AMI
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Self-Healing Asphalt by Heijmans
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Self-Healing Asphalt by epion
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Self-Healing Automotive Coatings by XPEL
Here at Croda, we’ve been working on developing the next generation of Self-Healing materials based on intrinsic methods. What is new?
• No external activation required to repair• Multiple repair cycles in the same location
• Restoring mechanical strength and protection
How does Self-Healing work?
There are different types of mechanisms that can produce a self-healing effect. These can normally be categorised into three separate groups.
Flow: The properties of the material allows it to distort and dissipate the energy of a scratch. Often using heat, the “shape-memory” effects cause the material to flow back to its initial state. High flow occurs at elevated temperatures and usually means that the material cannot be very strong and heavy damage cannot be healed.
Extrinsic: Materials that self-heal by utilising external additives. These are contained in microcapsules (tiny spheres) or vascules (tiny tubes) that are incorporated into the polymer matrix. When scratched or damaged, these break and leach into the gap where polymerisation takes place. A second scratch in the same location can no longer heal since the additive has already been activated.
Intrinsic: The chemical structure of the polymer can be designed to create polymer chains that can reconnect and repair after damage occurs by the reformation of bonds. The mechanism is usually facilitated by polymer chain mobility and reversible intermolecular bonding. The system must be flexible enough to facilitate polymer chain mobility, whilst not impacting mechanical properties. This is where Croda focuses.
Where can Self-Healing be used further?
Self-Healing materials can be applied to a multitude of different applications and industry areas; from electronic devices, furniture and wood coatings, to protective coatings for bridges and buildings, and technical rubber materials. There are multiple possibilities, inside and out.
A few key areas of interest are highlighted here:
Anti-corrosion coatings
In an industry where high performance is required, extremely hard and durable coatings dominate. These coatings contain a high loading of additives and other functional ingredients, which can compromise performance properties such as flexibility and toughness. Over time, traditional anti-corrosion coatings can fail, and once corrosion begins it is nearly impossible to stop. Self-Healing protective coatings can offer an alternative durable and cost-effective solution to corrosion protection, by autonomously healing cracks and scratches that result from bumps and bruises, and regain barrier properties.
Electronics
The electronics industry has been a major driving force in the development of novel materials. The demand for flexible and thinner displays has led to the need for improved materials, ensuring added features in the newest electronics do not compromise on the lifetime of the product. Self-Healing materials have the potential of becoming very useful within the electronics industry, in the construction of tiny interior components and external materials and displays. This will allow more durable, functional products that can last longer, even when damaged or dropped.
Who are we working with?
In order to understand Self-Healing materials on a fundamental level, Croda has an Open Innovation program with the renowned Delft University of Technology in The Netherlands, at the Novel Aerospace Materials group. Research has focused mainly on self-healing polyimides and polyurethanes, helping us to understand the healing mechanisms and other material properties. This Open Innovation project has been supported by IOP Self-Healing Materials in the Netherlands and is now supported by NWO. Since the start of this program, TU Delft scientists have successfully published their results, just click on the links below to the following articles:
- Effect of the Dianhydride/Branched Diamine Ratio on the Architecture and Room Temperature Healing Behavior of Polyetherimides
- Imaging the Molecular Motions of Autonomous Repair in a Self-Healing Polymer
- Identifying the Role of Primary and Secondary Interactions on the Mechanical Properties and Healing of Densely Branched Polyimides
- Understanding the Effect of the Dianhydride Structure on the Properties of Semi-aromatic Polyimides Containing a Biobased Fatty Diamine
- The bio-touch: Increasing coating functionalities via biomass-derived components
- A deconvolution protocol of the mechanical relaxation spectrum to identify and quantify individual polymer feature contributions to self-healing
How can you utilise this technology?
Croda is developing functional building blocks that can be used to formulate Self-Healing polyurethanes and polyimides based on intrinsic technology, meaning the product can heal over and over again in the same area.
We can also offer formulation advice depending on application area and required material properties, to ensure the best system for the job at hand.
We will share regular updates on our Self-Healing Innovation and if you would like to stay up to date, please register on our website.