3-D printing enables the rapid creation of precisely shaped items for everyday use, from customizable, engineered items such as vehicle parts and manufacturing prototypes, to patient-specific medical devices like stents and prostheses. Through use of computer programmed instructions, this technology is currently capable of making uniform items with micrometer precision. 3-D printing is already a revolutionary technology, but still cannot create the truly advanced materials found in living systems that adapt and transform upon stimulation by altering structures across length scales. For example, chameleons change their color by adjusting their skin structure at nanometer length scales. This research seeks to significantly advance the frontier of 3-D printing by introducing the new on-the-fly dynamic capability of tuning material structures down to the nanoscale. This capability will be achieved by designing self-assembling materials, where the self-assembly can be controlled by precisely adjusting the stresses in the printing process. This approach will enable chameleon-skin-like materials capable of rapid color adaptation to be made. This interdisciplinary team brings together expertise on making materials, testing how these materials flow, and printing these materials. This is then combined with advanced molecular simulation to design and evaluate possible materials capable of meeting the criteria for controlled on-the-fly printing of nano-scale structures. These new materials will benefit society and the U.S. by adaptably printing new items with potential applications in camouflage, antireflection coatings, metamaterials, and displays. The research will also involve the training of students with broad expertise spanning chemistry, engineering, and physics, via both student mentorship and educational outreach to students underrepresented in STEM fields.
This research will use the stresses in out-of-equilibrium 3-D printing processes to 'dial-in' hierarchical structural features in printed structures. A class of candidate materials known as bottlebrush block copolymers can form nanometer structures that readily deform under an applied stress. Bottlebrush block copolymers are a promising materials platform because they possess a large molecular design space. The PIs will develop and implement a screening methodology to explore this design space and determine optimal bottlebrush block copolymers for hierarchical printable materials. A holistic approach to computer-driven design will combine scalable synthesis, large-scale simulation, and rheological characterization to systematically design polymer molecules to yield desired, flow-induced nano-structures. This design procedure will be implemented to optimize 3-D printed nanostructured materials 'on-the-fly', culminating in a proof-of-concept of 3-D printed materials with heterogeneous photonic (i.e. color) properties. Along with this broad goal, this research will address fundamental questions in developing new, scalable polymer chemistry, driven self-assembly, and the rheology of bottlebrush block copolymers.
