Greg Grason, UMASS Amherst

Title: Intra-domain textures and chirality transfer in block copolymer melts

Abstract:

Self-assembled block copolymer (BCP) melts are a chemically-versatile platform for generating a rich spectrum of periodically-ordered nanostructures of various morphologies, from arrays of layers and columns to cubic arrays of spheres and bicontinuous networks. They are also a model system for understanding processes and properties of self-assemblies, more broadly. Decades of study of BCP assembly have uncovered the principles that connect molecular BCP structure to the translational order of the (scalar) composition profiles in the ordered states. In this talk, I will describe recent efforts to understand the generic, yet poorly known, patterns of orientational ordering of constituent chain segments that underlie the otherwise well-known “standard” BCP morphologies. From generic properties of the random-walk statistics in BCPs, we show that the direction and degree of alignment of segments varies non-trivially from place-to-place in self-organized domains, and from one morphology to another. Finally, we discuss how this orientation of order BCP assemblies has implications for new models of chiral block copolymers that aim to capture experimental observations of transfer of chirality from a constituent polymer backbone to the handedness of domain shapes at the mesoscale.