(537b) [Invited Talk] Chirality in Block Copolymers Is an Opportunity to Leverage Unique Thermodynamics

The role of chirality in self-assembly is challenging to understand because chirality is a geometric property at a given length scale regarding spatial arrangements that does not always translate into a thermodynamic driving force. Here we start with chirality at the conformational length scales (i.e. polymers adopting helical structures rather than spaghetti-like coiled structures) and interrogate its role in the thermodynamics of self-assembling systems comprised of such building blocks. Geometrically, a helix is determined by its curvature and torsion. In a polymer molecule, these conformations need to be described by the helical pitch, helical radius, and backbone stiffness (inversely related to thermal fluctuations). In this talk, we utilize a bead-spring approach to model helical polymers whose parameters can be tuned to bridge three ideals of polymer physics: the Gaussian coil, Kratky-Porod description for rod-like models, and Yamakawa’s helical wormlike chain model for helices. The models also incorporate excluded volume interactions which are necessary to study self-assembly. In the context of coil-helix block copolymers, we examine the role of different geometric characteristics in different regions in the phase diagram: the disordered region, the ordered lamellar region, and the order-disorder transition separating these two regions. Depending on the specific geometric characteristics of the chiral polymers, the thermodynamics is impacted in many unique ways. Sometimes, helicity can induce rod-like behavior and other times helicity may not significantly impact the self-assembled structure. This provides a rich framework to design novel helical polymers with specific desired properties.