(693b) Modeling Bottlebrush Polymers for Self-Assembly and Printing

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. The polymer science community has begun to leverage several unique properties of these molecules, including the suppression of entanglements and increased conformational stiffness. More generally, an increased number of molecular design parameters (i.e. side-chain and backbone length, grafting density) have been useful for engineering materials for applications such as soft elastomers, adhesives, responsive materials, and hydrophobic surfaces.

In this talk, I will focus on blocky bottlebrush polymers, which can be used to create materials that self-assemble into photonic crystals at >100-nm length scales, and thus exhibit vibrant ‘structural color’. We have been developing 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 simulations capable of predicting the equilibrium structure of individual bottlebrush molecules, we implement a coarse-graining scheme capable of capturing concentrations spanning both solution and melt behaviors, and reveals how the interactions between densely-grafted branches gives rise to conformational features seen in experiment. Combined with theoretical scaling arguments, this also allows us to predict the solution self-assembly of block bottlebrush copolymers and establishes molecular insight into how out-of-equilibrium processing affects structural color during printing, and can also be used to predict the behaviors of ‘shape-defined’ polymers. Overall, I will show how our computational and theoretical efforts inform materials design principles for the properties and processing of bottlebrush polymers.