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Harnessing Complex Macromolecular Conformations

Harnessing Complex Macromolecular Conformations

Seeks to understand the impact of chain conformations on macroscopic responses to applied forces and emphasizes topics related to the non-equilibrium behavior of polymers. 

After a century of macromolecular science, materials can now be developed by controlling conformations of polymers. Building on established connections between chain conformations and macroscopic properties at and near-equilibrium conditions, we hypothesize that we can access new regimes of material properties by incorporating zwitterionic groups, creating nonlinear polymer chains, and using external fields to manipulate chain conformations. Access to the new regimes will significantly expand the design space for developing responsive polymer systems with behavior inaccessible to linear neutral polymers. Using closely integrated experimental and computational studies, the Harnessing Complex Macromolecular Conformations (HCMC) theme will achieve the overarching goal of providing a predictive understanding of the link between chain conformations of zwitterionic polymers and macroscopic structure, properties, and responses to external stimuli. To achieve the overarching goal, our efforts will focus on three specific aims (SAs) focused on understanding conformations of polyzwitterions (PZs) in solutions and dry states while making correlations between electrostatics (SA1), topological effects (SA2), and processing (SA3):

  1. Understanding the conformations of PZs in complexes and copolymers. We will focus on understanding the effects of heterogeneous charge regulation, hydration, and solvent release on conformations of PZs in solutions when they are blended with polyelectrolytes, leading to the complexation of polymer chains and coacervation (liquid–liquid phase separation) in some instances. Furthermore, connections will be established between the chain conformations and strain responses of the polymers to applied electric fields in dry states.

  2. Control and evaluate topological effects in films containing PZs. Advances made in synthesizing topologically complex macromolecules (geometrical topology) and compositions such as graft copolymers and knotted polymers provide a library of materials in which topological effects can be easily tuned by varying chain architecture and measuring responses to various nonequilibrium conditions. We will establish connections among the nonlinear chain architectures of PZs, their properties, and their behavior near surfaces.

  3. Elucidate the role of processing and rheology on structured PZs. Understand the rheological properties of PZs to design novel yield-stress fluids capable of undergoing solid-like to liquid-like responses with the changes in temperature, salt, and mixing protocols.

These three SAs will provide critical understanding of the underlying entropy-driven processes that underpin technology development in applications for energy storage, flexible electronics, polymer upcycling, 3D printing, and antifouling membranes.