Materials Science and Engineering Special Seminar


David Simmons, Department of Polymer Engineering, The University of Akron

Date Mon, 01/29/2018

280 Materials Research Laboratory

Time 10:00 am

Materials Science and Engineering

Event Type Seminar/Symposium

“Evolutionary molecular design for scientific discovery in sequence-specific polymers and glass-forming materials”


The last decade has seen the emergence of a new frontier in polymer chemistry: the facile synthesis of copolymers with specific monomeric sequences. This advance may be the key to realizing synthetic polymers exceeding the performance of biopolymers such as proteins and DNA. Achieving this goal will require solutions to two challenges. First, the design space afforded by even a single sequence-specific polymer can be beyond astronomical in scale. How are we to reproduce, on a human timescale, the billions of years nature has dedicated to designing these complex molecules? Second, the last century of polymer physics has focused largely on establishing theoretical understanding at the level of mean chain composition or statistical descriptions of sequence. Realizing a new generation of sequence-specific polymeric materials demands a reimagining of standard theories of polymer physics to understand the behavior of sequence-specific polymers. More broadly, this problem represents an extreme case of the challenge of design of polymers and soft materials, where chemical design spaces are large and predictive theoretical understanding often lacking. Here I describe a new approach to this problem, combining molecular dynamics simulations, machine learning, and evolutionary algorithms to design sequence-specific polymers with extremal properties and then reverse-engineer their underlying physics. We apply this strategy to design model sequence-specific copolymer compatibilizers that reduce the energy of a polymer/polymer interface more efficiently than sequence-nonspecific surfactants. Study of these designed sequences ultimately yields new physical insight into the role of chain sequence in polymer surfactants. We specifically show that sequence specificity in this system emerges from tradeoffs between interfacial entropy and enthalpy, with implications for the design of sequence-specific surfactants more broadly. These results suggest new opportunities for control of surface interactions via designed sequence-specific surfactants and ultimately point to the prospect of a new century of polymer science built around designed sequence specificity. Finally, we demonstrate that this strategy for materials design and understanding is extensible to the design and understanding of other classes of soft materials. We employ a hybrid computational/informatic genetic algorithm to design model molecules with targeted glass formation behavior – a problem of relevance to material challenges ranging from next-generation battery materials to lightweight structural materials.