A team of researchers has developed a new material that is not only stretchy but impermeable to gases and liquids. This is something that this kind of material is usually not good at. This material could be useful in the production of flexible batteries and wearable electronics.
Designing materials often requires trade-offs between specific properties. If you want something that prevents the ingress of gases or liquids, you need a hard, rigid material. On the other hand, if you want something a little more flexible, it should be at least partially permeable by gas or liquid.
But in a new study, researchers at North Carolina State University (NCSU) have developed a new material that can do both. The key is a strange alloy known as eutectic gallium and indium (EGaIn). It consists of two soft metals that are in liquid form at room temperature. EGaIn has proven to be a versatile material and has recently been used as a carbon-trapping catalyst in dissolvable implants and stretchable and twistable electronic devices.
To create the new material, the team wrapped a thin layer of EGaIn with an elastic polymer. Inside the polymer is a series of tiny glass beads that prevent EGaIn from pooling in one place. This makes the new material a stretchy and flexible polymer, with liquid metal at its core, effectively preventing the passage of gases and liquids.
In testing the material’s effectiveness, the team measured whether the liquid metal would evaporate over time and whether oxygen could escape from the closed polymer container. In both cases, no liquid or gas loss was detected, indicating an effective barrier.
In more detailed experiments, the researchers tested how well the polymers act as hermetic seals for stretchable electronic devices such as batteries and heat transfer systems. Again, the polymer helped both devices do their part, keeping the battery’s capacity high for over 500 cycles and increasing the thermal conductivity of the heat transfer system.
Finally, the team added a signal transmission window to the polymer and demonstrated that it can also be used to pass wireless communications. Overall, these experiments demonstrate that flexible, impermeable materials can be used for a variety of applications.
One possible drawback is that EGaIn is relatively expensive. But the team says the study didn’t focus on cost, so there should be room to optimize materials to reduce costs. One of his methods they suggest is to use a thin film of EGaIn.
A study was published in a journal chemistry.
Source: NCSU
