Charles Sing

Polymer Physics, Statistical Mechanics, and Computer Simulation

Sing Research Group     Directory Listing

Charles E. Sing
Charles E. Sing

Research Statement

Our research uses simulation and theory to understand polymer materials such as those in modern-day consumer products, advanced responsive or adaptive materials, and in biological systems. Our primary goal is to inform how polymers can be engineered at the molecular level, taking inspiration from biology where complex structure and function arises from processes occurring on disparate length and time scales. We integrate statistical mechanical theory and coarse-grained models to understand polymer physical phenomena, addressing fundamental physical problems using a unique brand of molecular engineering that combines accurate physicochemical models with first principles theory, in close collaboration with experimentalists. See below for a non-comprehensive list of research areas.

Charge-Driven Polymer Assembly

We are interested in how molecular details such as primary polymer sequence, macromolecular architecture, and electrostatic environment govern the thermodynamics and self-assembly of charged polymers. Our work probes the connections between molecular structure and thermodynamic phase behavior in complex coacervates, a class of charged polymer materials, using theory and simulation. Coacervates are broadly useful in applications ranging from personal care products to stimuli-responsive materials, and as analogues for biomolecular condensates. In this last application, we have made fundamental advances by studying the effect of charge sequence on assembly properties, and we seek to lay the foundations for designing polymers with built-in self-assembly instructions.

 

Out-of-Equilibrium Polymer Dynamics

We are interested in how hydrodynamics, polymer architecture, and intermolecular interactions influence the dynamics of polymers in solution. We have developed new computational methods for simulating out-of-equilibrium semidilute polymer solutions, in order to demonstrate how polymer architecture and hydrodynamic interactions govern the dynamics and structure of polymers in strong flows. Our research has revealed the importance of architecture-hydrodynamic coupling in flowing polymer solutions, and the presence of large conformational fluctuations driven by polymer-induced local flows in non-dilute systems. Much of this work has been in collaboration with Prof. Schroeder, and will provide insights important to the solution processing of polymers, such as in printing or coating processes

Brush-like Polymer Assembly

We are interested in how molecular architecture governs molecular interactions and assembly in polymer solutions. Our work has established models of architecture-mediated interactions in the solution behavior of highly-branched polymers. This includes coarse-graining procedures that allow us to simplify the structure of these brush-like macromolecules, while retaining key physical attributes and interactions. We use these advances in coarse-grained polymer models to explore the interplay between polymer branching and conformation, molecular interactions, and self-assembly in dense solutions. We collaborate with Profs. Diao, Rogers, and Guironnet on understanding the design of these systems for printing materials that exhibit structural color that is tunable ‘on-the-fly’ via processing conditions.