Highly soft and elastic materials are desired for uses in reconstructive surgery, cell differentiation, and antifouling surfaces. The project goal is to design solvent-free ultra-soft materials by constructing polymer networks of bottlebrush-shaped macromolecules. The new materials will possess a major advantage with respect to multicomponent polymer gels that are prone to segregation and escape of constituting liquids. In addition, the bottlebrush architecture allows abundant incorporation of specific chemical functionalities that provide new abilities such as shape control, imaging contrast, and response to external stimuli. The research will focus on the synthesis of advanced macromolecular architectures and fundamental understanding of the structure-property relations between the hierarchical structure of molecular bottlebrushes and mechanical properties such as stiffness, elasticity, and toughness. This project may lead to novel materials that offer a vast array of functions and stimuli responses enabling programmable shape transformations and non-invasive manipulation of implants within biological tissue. Moreover, the interdisciplinary research will ensure maximum opportunity for integrating science and education based on the multidisciplinary training of students and postdoctoral researchers, partnerships with high schools, and involvement of underrepresented groups in science and technology.
The project is focused on the design of novel functional materials possessing a unique combination of properties: neat chemical composition, exceptionally low elastic modulus, programmable shape, and acoustic response. Specifically, the research will explore elastomers constructed of bottlebrush-shaped polymers that contain crystallizable and H-bonding moieties in their side-chains and backbones. Through molecularly constrained crystallization and abundant chain-end functionalities, finely interwoven structures composed of a permanent covalent network and a temporary scaffold of crystallites and hydrogen bonds will be created to enable stimulus-responsive control of mechanical properties and object shapes in an unprecedented range. The unique mechanical properties of bottlebrush elastomers stem from the hierarchical structure, wherein covalent and excluded volume architectural constraints amplify and direct molecular forces at different length scales. Fundamental understanding of the hierarchical relation between molecular forces and supramolecular constraints, and its impact on material properties represents the core intellectual challenge of the project. Looking towards practical applications, the research will explore the potential of bottlebrush elastomers for creation of shape-changing implants that can be navigated and activated inside a biological tissue non-invasively and remotely. This interdisciplinary research project will ensure maximum opportunity for integrating science and education based on the interdisciplinary training of students and postdoctoral associates, partnerships with high schools, and involvement of underrepresented groups in science and technology.
