NSF CAREER Award To Develop Stronger and More Versatile Adhesives
MIE Assistant Professor Ruobing Bai received a $650,000 NSF CAREER Award to improve the functionality of soft sticky adhesive materials so that they do not easily crack or break and can rapidly switch between adhesive and non-adhesive states.
Ruobing Bai, assistant professor of mechanical and industrial engineering, received a $650,000 National Science Foundation CAREER Award, “Interfacial Fracture, Fatigue, and Switchable Adhesion of Soft Sticky Adhesives”, to improve the functionality of soft sticky adhesive materials so that they do not easily crack or break, and can rapidly switch between adhesive and non-adhesive states. He is using a novel approach that focuses on the structures and interactions within soft sticky adhesive materials.
The soft sticky materials, commonly known as pressure sensitive adhesives, have been around for decades. Beyond their usage in many industrial, manufacturing, and medical products, they are the material that makes Post-it®Notes stick. The switching capability is increasingly important in industrial and manufacturing processes that use adhesives with robotic devices or other equipment to attach and disengage from surfaces.
“Most approaches to improve soft sticky material longevity and switching capabilities have focused on chemical- and physics-based investigations,” says Bai. “The mechanics of the materials has been left largely unexplored.”
The discipline of fracture mechanics, which is the study of how cracks form and propagate in materials, began more than 100 years ago. “Fracture mechanics showed great success with glass, metals, and rubber,” Bai says. “That is not the case yet with these materials.”
As an example, Bai hopes to identify the underlying mechanical factors that contribute to such problems as fracture failure, which is when the adhesive either separates entirely from a surface or breaks or tears, leaving a sticky residue.
Bai will integrate experimental and computational modeling approaches to first identify what mechanical properties could be contributing to the limitations, and investigate mechanical interactions on the nanoscale, microscale, and macroscale levels.
“We need to have experimental data because this is so complex,” Bai says. “It’s multi-scale by nature.”
Specifically, Bai aims to understand the interplay between four key factors: interfacial bonding, which is the bond between two different types of materials; bulk dissipation, which relates to the dissipation of energy within the material itself; stimuli-responsiveness, which examines how a material changes in response to external stimuli, such as heat or light; and interfacial geometry, which examines the shapes and dimensions on a material’s surface at their points of intersection.
He will initially focus on using heat as a method to create the dynamic switching capability that would enable the material to unstick and reattach repetitively. Another option could be incorporating light-absorbing materials into the adhesives that would react when light is applied.
In addition to these investigations, which will include conducting experiments to measure the material’s properties, performing simulations, and advancing theoretical models, Bai plans to create a new switchable soft sticky adhesive that reflects his findings.
Advances in these materials could also contribute to sustainability. Manufacturers could use the adhesives to replace screws or other hardware devices used to hold components together. The adhesives could eventually be removed without damaging components, making it more likely that the components could be recycled and reused.
Abstract Source: NSF
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