There are a number of applications for materials that have the ability to adhere strongly to a surface under certain circumstances, and to exhibit weak adhesion in other circumstances. Materials with variable adhesion are needed for applications such as integrated circuit fabrication, solar cell manufacturing, medical tapes, and climbing robots. While adhesion at an interface can be altered through external forces such as temperature or magnetic field, a much simpler design is to design materials with variable adhesion that can be altered depending on the direction of the applied force. This award supports fundamental research that will enable the design and fabrication of structured composite materials that offer the ability to significantly vary adhesion by changing the direction of loading applied to the adhered interface. These composite materials with variable adhesion have uses in manufacturing, healthcare, and consumer products, thus this research will benefit U.S. industry and the economy. This award will also result in the training of students in several disciplines, including mechanical engineering, microfabrication, polymer processing, and materials science. This training in key engineering areas will help to enhance the technical workforce and improve U.S. competiveness.
The proposed composite materials provide the ability to significantly alter the effective adhesion of an interface by changing the loading direction. While the basic principles of these materials have been demonstrated through preliminary experiments and modeling, fundamental research is needed to establish an understanding of the relationship between the processing, structure, and adhesion properties of structured composite materials. This research will use analytical and computational mechanics models to investigate the relationship between the structure of the composite and the failure behavior of the interface. Experiments will be performed to characterize the adhesive and constitutive properties of the constituent materials of the composites as input for the models. A combination of microfabrication and polymer molding techniques will be used to fabricate structured composite materials that will then be extensively characterized under various loading conditions. The combination of modeling and experiments in this research will lead to new fundamental understanding of structured composite materials and will enable the rational design of materials with variable adhesion.
