CAREER: Chemically specific polymer models with field-theoretic simulations

NONTECHNICAL SUMMARY

Polymers are long chain-like molecules that underlie diverse technologies ranging from surfactants and adhesives to biomaterials and batteries. Polymers also play a critical role in emerging technologies such as flexible electronics, organic solar cells and next-generation filtration membranes. In all of these applications, the chemical details of the polymers are critical: small chemical modifications to polymers can result in materials with drastically different properties.

Unfortunately, it is exceptionally difficult to predict how changes in polymer chemistry will affect the resulting material properties and so new materials must be laboriously optimized through trial-and-error experimentation.

This CAREER award supports the development of a new computational method that will accelerate the design of new polymeric materials using simulation. The basis for this new approach relies on an alternative strategy for simulating polymers that is considerably faster than existing techniques and can enable calculations that are currently intractable with existing methods.

This project will extend this new method to include specific information about a polymer's chemistry while remaining efficient enough to predict the large structures inherent to polymeric materials. By accurately predicting the structure of polymers across this wide range of length scales, this new computational tool has the potential to significantly accelerate the design of new polymers for both existing and emerging applications.

This CAREER award also supports educational and outreach activities that will train students at multiple education levels in modern computation. These activities will: (1) initiate a new coding club to provide coding experiences for middle-school girls, (2) expose undergraduates to computational research through Drexel's co-op program, and (3) train graduate students in polymeric simulations with online and freely accessible lectures and assignments.

This educational platform incorporates key elements from the technical project into age-appropriate activities that will link the discovery process with its dissemination. TECHNICAL SUMMARY

One of the defining features of polymeric materials is a hierarchy of length scales that involves a complex interplay between monomer (1 nm), molecular (10 nm) and mesoscopic (100 nm) features. This hierarchy of length scales makes it challenging to design new polymeric materials because it is difficult to anticipate how chemical changes at the smallest length scales will propagate up to the largest length scales in a material.

In this project, a new simulation method will be pursued that can simultaneously resolve both monomer-level chemistry and mesoscopic length scales within a polymeric material. The basis for this strategy is a new "multi-representation" approach where particle-based and field-theoretic simulations are linked together into a unified framework. Preliminary results indicate that this new method can accelerate calculations by several orders of magnitude yet involves no approximation or information loss relative to existing techniques.

As such, this new framework has the potential to enable polymer simulations that are currently intractable and could provide new fundamental insights into how mesoscale structures emerge from monomer-level chemistry.

This CAREER award supports the development of this new simulation method, the extension of the method to chemically specific interaction potentials and its application to intrinsically disordered polypeptides. More generally, this project also explores the fundamental intersections between particle and field-based simulations and how these methods can be combined together to provide facile access to molecular configurations, mesoscopic structure and free energies.

This project will also advance the field-theoretic simulation method and will lead to the development of new tools and numerical methods that will broaden the applicability of this powerful, yet nascent, simulation technique.

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.