The world is filled with a symphony of sounds and vibrations, both soothing and annoying. The ability to selectively tune out noises of a certain frequency has long been a dream for many individuals. But what if this dream could become a reality? Researchers at the University of Illinois Urbana-Champaign have made significant strides in the field of polymer networks, developing materials that can selectively absorb specific frequencies of sound and vibrations.
Materials science and engineering professor, Chris Evans, and his team set out to explore the design of polymer networks to understand their energy-absorbing abilities. By incorporating dynamic bonds into the network, they aimed to control the response of the material to different frequencies. The results of their research, recently published in Nature Communications, demonstrate promising advancements in sound and vibration damping.
Before delving into the research findings, it is important to grasp the fundamentals of polymer networks. Polymers are long chain molecules composed of repeating units. Some polymers have branches, while others are highly cross-linked. In cross-linked polymers, individual chains are connected by covalent bonds, much like a net. These cross-link points play a crucial role in the behavior of the material.
Incorporating dynamic covalent bonds into the polymer network allows it to rearrange its structure based on changes in the environment. This flexibility can enhance the material’s properties, such as stiffness and flowability. The key advancement in this research lies in the use of dynamic covalent bonds that can exchange with each other at different timescales. By utilizing orthogonal bonds, the team generated multiple relaxation modes, effectively damping sound and improving mechanical properties.
Evans emphasizes the significant influence of the polymer chain’s connectivity on its energy dissipating processes. The team created a series of polymers with controlled architectures and backbones to investigate the impact of these factors. Linking the chains periodically along the backbone proved to be more effective in absorbing specific frequencies compared to only linking them at the ends.
Despite the promising findings, the materials used in this research do have limitations. The incorporation of dynamic bonds ultimately leads to material flow over time. While this characteristic is acceptable for certain applications, like a soldier’s helmet, it poses challenges for others, such as earplugs. However, Evans and his team are actively working on developing self-standing materials to overcome this obstacle. Additionally, their future plans involve further incorporating dynamic bonds to broaden the range of frequencies that the polymer can absorb.
The research conducted at the University of Illinois Urbana-Champaign has shed light on the potential of polymer networks for sound and vibration damping. By manipulating the molecular-scale chemistry of the material through the incorporation of dynamic bonds, researchers have demonstrated the ability to selectively tune out specific frequencies. This breakthrough has significant implications for various fields, including hearing protection, blast-related injuries, and noise pollution. As technology continues to advance, the dream of selectively controlling the soundscape around us may soon become a reality.