DMREF: Engineering the On-The-Fly Control of 3-D Printed Block Bottlebrush Assemblies via Dynamic Bonds and Materials Processing

点击翻译按钮获取中文摘要

Biology is capable of creating materials with truly complex properties; for example, chameleons can change their color by stretching their skin in ways that affect nanoscale structure, and muscle proteins can controllably break and reform to act as ‘shock absorbers’ that dissipate energy. These biological materials share a foundational principle, which is that molecular interactions have evolved to precisely control both the nanoscale structure and dynamics that govern function. Synthetic soft materials, however, rarely reach this level of sophistication due to the challenge of controlling both molecular arrangement and motions simultaneously. This Designing Materials to Revolutionize and Engineer our Future (DMREF) project seeks to bridge this gap by ‘dialing-in’ material properties on-the-fly by using processing to exert spatial and temporal control over molecular interactions. This will be achieved by using processing flows in 3-D printing to control molecular assemblies, along with breaking/reforming of chemical bonds to relax or arrest the material structure. Automated printing and characterization will facilitate materials discovery through machine learning protocols and will inform molecular design principles. This interdisciplinary effort will bring together academic researchers and scientists from the Air Force Research Laboratory (AFRL) who have combined expertise regarding making and characterizing materials, automating synthesis and processing, and using molecular simulation and machine learning. The effort will harness nanoscale structure and dynamics to create materials that emulate the complicated functions seen in biology. These new materials and processing capabilities will benefit society and the U.S. by on-the-fly printing new items with potential applications in camouflage, metamaterials, radiative cooling, energy conversion and storage devices, 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 from groups historically underrepresented in STEM fields.This project will combine the stresses in out-of-equilibrium 3D printing processes, along with dynamic (e.g. reversible or triggerable) bond chemistries and tunable molecular architecture, to establish an automated manufacturing/materials discovery protocol. A class of branched macromolecules known as bottlebrush block copolymers can form nanoscale assemblies, which can be distorted under an applied stress and are sensitive to branch length and density. These materials are especially useful because they can be decorated with chemical functional groups that affect properties via inter-bottlebrush interactions. In line with the Materials Genome Initiative (MGI), the project will establish a methodology to discover materials in this rich design space, using computer-driven design and physically-guided machine learning as a complement to automated synthesis, characterization, and processing design. The goal will be to use structural color as a proxy for printed materials with tunable ‘on-the-fly’ nanoscale structure, with dynamic bonding incorporated to freeze-in or temporally modulate these optical properties, and ultimately to incorporate stimuli-responsive functionality into these soft materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.