INS7-1028
Leveraging Polymer Conformational Entropy for Directed Self-Assembly of Colloids
Topic
S7. Innovations in Polymeric Composites: From Design and Processing to Industrial Applications
When and Where
Sep 30, 2026
16:25 - 16:50
Room 107
Session Chairs
Jin Chul KIM
Presenter(s)
Sangwoo Lee (Rensselaer Polytechnic Institute)
Co-Author(s)
Abstract
Phase transitions and the associated structures of spherical colloids are fundamental topics in materials research as they reveal how nature determines material structures. Over the last few decades, a library of topologically close-packed structures (TCPs) formed by deformable spherical colloids has been well documented and explained. However, surprisingly, the origin of the polymorphism of close-packed structures of equal spheres has remained elusive. In this talk, we discuss a new strategy that leverages the conformational entropy of polymer chains to control the polymorphism in close-packed block copolymer micelles. Among the polytypes of close-packed structures, face-centered cubic (FCC) is the most stable structure due to its advantage in lattice configurational entropy. Indeed, FCC is the dominant polytype observed in colloidal systems. However, other polytypes, such as hexagonal close-packed (HCP) and random stacking of 2D-HCP layers (RHCP), are also frequently observed, yet their thermodynamic origins remain unclear. Using model block copolymer micelles, we show that a systematic shift in the polytypes from FCC to HCP via RHCP is achieved by introducing long corona chains into the interstitial spaces of the colloidal crystals. We explain this shift through the competition between the conformational entropy of polymer chains in the interstitial spaces, which is maximized in HCP, and the lattice configurational entropy preferring FCC. The use of polymer conformational entropy offers a new strategy for controlling the self-assembly of colloids beyond tuning the classical interparticle interactions.
