The roles of entropy and chirality during self-assembly of helical polymers

ABSTRACT

For several decades, polymer conformations have typically exhibited coil-like or rod-like behaviors with well-understood thermodynamic behaviors. The recent synthesis of helical polymers, where the molecules tend to form helical (spring-like) shapes that can additionally behave like coils or rods, requires new understanding of the relationship between chain shape and entropic driving forces. As a wide variety of chemical building blocks are known to form helical polymers, such insights can lead to designing novel polymeric materials. In this talk, I will discuss our simulation model for appropriately modeling helical polymers of several geometries. Using molecular dynamics simulations, free energy calculations, and AI-assisted sampling of the phase diagram, we can characterize the thermodynamic behavior in great detail. Two systems will be presented: (1) a melt of linear coil-helix block polymer and, (2) a solution of helical polymers. Interestingly, we see that the distinction between coil and helix is not sufficient to describe the behavior, but the specific details of the geometric shape (i.e. pitch and radius) can produce a wide variety of results for helical polymers.

BIOGRAPHY

Poornima Padmanabhan is currently an Associate Professor at Rochester Institute of Technology in the Department of Chemical Engineering. She received her B. Tech in Chemical Engineering from the Indian Institute of Technology (IIT) Madras and Ph.D. from Cornell University. Her research interests are in the thermodynamics of polymers and soft materials. In 2022, she received an NSF CAREER award to study the interplay between chirality and thermodynamics, and to improve engineering pedagogy by designing activities targeted at improving spatial thinking skills in first year engineering students. In 2024, her work was recognized at the ACS PMSE Early Investigator Symposium.