Branching represents a powerful way to engineer polymer materials and is a key architectural motif in macromolecules ranging from commodity plastics to biopolymers. The physical ramifications of these branches on material properties have been studied since essentially the dawn of polymer science; however, recent advances in polymer chemistry have led to increased interest in a class of highly branched ‘bottlebrush’ polymers. These molecules lead to materials with unique properties, including the suppression of entanglements and increased conformational stiffness. Bottlebrush polymers have been used for applications such as soft elastomers, adhesives, responsive materials and hydrophobic surfaces.

In this talk, I will focus on how blocky bottlebrush polymers can be used to create materials that self-assemble into photonic crystals at >100-nm length scales, and thus exhibit vibrant ‘structural color’. Together with experimental collaborators (Profs. Rogers, Diao, Guironnet), we can show how the out-of-equilibrium processing of these materials can be used to print different structural colors on-the-fly with the same material. Our contribution to this multi-PI effort has been to develop models that can predict this behavior at the molecular level, overcoming the challenge of addressing both the side-chain and self-assembly length scales. Building from theory and simulation capable of quantitatively predicting the equilibrium structure of individual bottlebrush molecules in dilute solution, we implement a coarse-graining scheme that predicts the solution self-assembly of block bottlebrush copolymers and establishes molecular insight into how out-of-equilibrium processing affects structural color during printing. Overall, I will show how our computational and theoretical efforts inform – and are informed by – experiments to co-design materials properties and processing.

Charles Sing, Ph.D.  is the James M. and Karen S. Morris Faculty Scholar and Professor of Chemical and Biomolecular Engineering at the University of Illinois at Urbana-Champaign. He received his BS and MS in polymer science from Case Western Reserve University in 2008, and his Ph.D. in materials science from MIT in 2012. Prior to starting at Illinois in 2014, Dr. Sing was a postdoctoral fellow at Northwestern University. His research interests are broadly in the areas of computational and theoretical polymer physics. Current projects focus on molecular and sequence properties of polyelectrolyte solutions, out-of-equilibrium rheology of semi-dilute polymers, polymers with nonlinear architectures, and charge and penetrant transport in polymers solutions and networks. He has received several honors, including an NSF CAREER Award. He has been recognized as an ACS PMSE Young Investigator, a UIUC Helen Corley Petit scholar, one of AIChE’s ’35 Under 35’, and as the 2024 Dillon Medalist by the American Physical Society.