Many studies have focused on developing materials for conventional acoustic applications, such as ultrasound imaging, sound insulation, and geological logging. However, the design of materials that actively respond to sound and concurrently shift their acoustic and optical characteristics remains in its infancy. The goal of this project is to design acoustically responsive materials that alter their chemical structure, physical properties, and object shapes whenever they interact with sound waves enabling active modulation of acoustic properties including speed of sound, attenuation, and phononic band gaps. If compared to electromagnetic radiation, sound waves possess unique physical characteristics as they readily propagate through optically non-transparent materials, including liquids, solids, and gels (e.g., human body), where direct application of conventional stimuli, such as light and electric fields, is either physically or physiologically prohibited. This enables non-invasive interrogation of a wide range of materials properties and remote activation of various mechanochemical processes. Moreover, similar to electromagnetic radiation, sound can be focused both in space and in time. This opens intriguing opportunities to perform local modifications in a time-controlled, sequential manner. These materials may be utilized both in materials engineering for acoustic lithography and self-healing and in biomedical applications including non-invasive surgery, diagnostics, and drug-delivery.
The project goal is to develop a new direction in materials design wherein fundamental changes in materials properties are activated by sound waves that concurrently shift acoustic, optical, and geometric characteristics of macroscopic objects. The research activities pursue three strategic objectives. First, develop fundamental understanding of hierarchic correlations between the multi-scale architecture of complex macromolecules and mechanical properties of materials assembled of these molecular mesoblocks. Theoretical studies will provide guidelines for synthesis of materials with an extraordinarily broad range of elasticity, strength, and toughness that are currently not available in conventional polymer systems. Second, study the interaction of sound waves with stimuli responsive polymer systems and explore different activation mechanisms that shift density, modulus, compressibility, and shape. Understanding the feedback between acoustically triggered changes in materials properties and the corresponding shifts in acoustic characteristics represents an intellectual challenge of this proposal. Third, create a novel class of materials that can be activated, actuated, and navigated remotely using acoustic fields in a programmable and time-resolved manner. An anticipated culmination of this project is acoustically transformative materials that not only respond to sound but also fundamentally change their physical properties, object dimensions, and acoustic and optical characteristics. The collaborative nature of this project will ensure interdisciplinary training of junior researchers in polymer synthesis, physical experiments, and theory. The project also provides opportunity for broadening participation of underrepresented groups and fostering infrastructure for collaborative research.
