Researchers have been exploring the potential of graphene, a supermaterial made up of layers of carbon atoms arranged in a honeycomb structure, for various applications such as bendable electronics, new batteries, and composite materials for aeronautics and space flight. However, one of the challenges in developing graphene-based materials has been creating films that are both elastic and tough. In a recent study published in the journal Angewandte Chemie, a research team led by Xuzhou Yan at Shanghai Jiao Tong University has introduced a new method to address this challenge.
The team’s approach involved cross-linking graphene nanolayers using mechanically interlocked molecules known as rotaxanes. Rotaxanes consist of a ring-shaped molecule threaded onto a molecular chain, with bulky groups preventing the ring from coming unthreaded. By incorporating rotaxanes into the graphene structure, the researchers were able to enhance the mechanical properties of the film. Specifically, the presence of rotaxanes increased the tensile strength, stretchability, and toughness of the graphene-rotaxane foil, making it more resilient to stretching and bending.
When the graphene-rotaxane films were subjected to stretching or bending, the intermolecular forces between the ring and the molecular chain had to be overcome, leading to an increase in tensile strength. This motion eventually caused the molecular chain to slide through the ring, lengthening the rotaxane bridges and allowing the layers of graphene to slide across each other. As a result, the film exhibited a significant increase in stretchability compared to films without rotaxanes, with the ability to be stretched up to 20% without being damaged.
In addition to its enhanced mechanical properties, the graphene-rotaxane foil retained its high electrical conductivity even when stretched or bent. The researchers also demonstrated the practical applications of this material by incorporating it into a simple grasping tool equipped with mechanical joints actuated by the new foil. Overall, the study highlights the potential of rotaxane-crosslinked graphene films as versatile materials for various applications requiring both flexibility and strength, such as flexible electronics and mechanical devices.
The development of graphene-rotaxane films represents a significant advancement in the field of materials science, offering a solution to the challenge of creating elastic and tough graphene-based materials. By utilizing rotaxanes as bridging structures, the researchers were able to enhance the mechanical properties of graphene films, making them more resilient to stretching and bending while retaining their high electrical conductivity. These findings have implications for the development of flexible electronics, composite materials for aerospace applications, and other innovative technologies that require materials with a unique combination of properties.
