CAREER: Simulations to Inform the Design of Force Responsive Copolymer Materials

This award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2). NONTECHNICAL SUMMARY

Plastic materials are surrounding us in our everyday life and are essential to our way of living, from construction materials to cell phones, polymers (long macromolecules made from repeating units) are an integral part of modern materials. Aside from their wide technological applications, they also pose risks to human health and cause significant environmental pollution.

Because of this, it is important to work on sustainable polymers with precisely tuned functions, which can have many applications from sensors, failure mechanics, self-healing materials, to biological materials. Particularly interesting are polymers which will respond to external forces, for example a deformation. Force-responsive units, called mechanophores, can be incorporated into polymer chains.

The main goal of this work is the careful design of the host bulk polymer material to control the activation of the embedded force-responsive unit. This will be addressed by using coarse-grained molecular dynamics simulations, where each polymer is represented by beads connected by springs. Using simulations, the relevant time- and length-scales can be resolved. The results can be used to guide materials design for high-performing, precisely tuned materials.

Outreach and education are integral to this CAREER program and all activities are directly tied into the research by introducing concepts important to the project. The PI will promote the participation and retention of underrepresented groups in STEM, by establishing a summer school program for underrepresented groups. Computational modules will be integrated into teaching and will increase students' confidence and physical intuition when dealing with complex concepts and equations.

Training undergraduate and graduate researchers from diverse backgrounds in interdisciplinary and transferable skills will also actively support underrepresented groups and enable broad participation in the soft matter and polymeric materials community. TECHNICAL SUMMARY

This CAREER award supports computational research and education on force-responsive polymeric materials. Force-responsive units in polymers are important for a wide range of applications, from sensors, failure mechanics, self-healing materials, to biological materials. The ability to design and build new stimuli responsive, high-performing, and sustainable polymeric materials is essential for all these applications.

Critical to being able to apply these materials is a microscopic understanding of what forces are present and how they propagate through the material. This is a challenging fundamental question that is out of reach with most experimental techniques. This project seeks to develop a framework to identify the key parameters governing force transport through polymeric materials; these parameters can then be used to inform experimental design.

The overarching premise of this work is that by careful design of the host bulk material the activation of embedded force-responsive units can be precisely controlled. The materials design challenge will be tackled using coarse-grained molecular dynamics simulations to study micro-phase separated copolymer materials. Simulation models developed by the PI are ideally suited to address these challenges by resolving the relevant length- and time-scales.

The outcomes will be fundamental insights into micro-scale force transport, and testable design paradigms for chain architecture and physical parameters. This work has the potential to be applied broadly to many other soft materials, where insights gained into force transport from the macroscopic to microscopic scale are essential.

Outreach and education are integral to this CAREER program and all activities are directly tied into the research by introducing concepts like polymer conformations, phase separation, and network formation, which are integral to the proposed research. The PI will promote the participation and retention of underrepresented groups in STEM. A K-12 summer school program for underrepresented groups will be established.

Computational modules will be integrated into teaching, where a powerful combination of guided inquiry learning exercises with computational apps will increase students' confidence and physical intuition when dealing with complex concepts and equations. Training undergraduate and graduate researchers from diverse backgrounds in interdisciplinary and transferable skills will also actively support underrepresented groups and enable broad participation in the soft matter community.

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.