Speaker：Zhengang WANG (California Institute of Technology)

Time：10:30 AM on December 13, 2025

Location: C1-b115, GuangzhouInternational Campus,SCUT  

Abstract:

Ionic interactions provide a powerful and tunable means to direct polymer phase behavior, with applications in solid-state batteries and polymer compatibilization. This talk explores two key systems—neutral-charged block copolymers and ion-functionalized polymer blends—using an electrostatic fluctuation-augmented self-consistent field theory.For AB block copolymers with partially charged A-blocks, we demonstrate that ion correlations induce a chimney-like phase diagram, but dielectric contrast between blocks weakens the chimney-like feature. As the A-block charge fraction increases, counterions shift from interfacial accumulation to more uniform distribution within the A-domain. Notably, smaller counterions promote localized ion distributions, leading to hierarchical nanostructures (e.g., alternating layers, concentric cylindrical shells, and spherical shells) in lamellar, cylindrical, and spherical phases, respectively. These findings are in general agreement with literature data on neutral–charged diblock copolymers and salt-dope diblock copolymers. In the second part, we examine polymer blends where each chain is end-functionalized with a single oppositely charged group. Strong ion correlations effectively link the polymers, inducing phase behavior resembling that of neutral block copolymers. However, the order-disorder transition occurs at a significantly lower critical χN than in neutral systems. Additionally, ion localization persists even in fully miscible blends. These findings highlight the critical role of ionic interactions in tailoring polymer self-assembly for advanced materials.

Biography: 

Professor Zhen-Gang WANG is an internationally renowned theoretical physicist specializing in polymers and soft matter. His research focuses on the thermodynamics and kinetics of polymer solutions, mixtures, and copolymers; surfaces and interfaces; liquid crystals, colloids, and gels; electrostatic interactions in soft matter systems; biophysics of DNA and RNA; virus self-assembly; and biomembrane physics. In 2001, he was elected as a fellow of the American Physical Society. In 2008, he was awarded the Richard P. Feynman Award for Excellence in Teaching at Caltech. In 2025, he was elected as a member to the National Academy of Engineering in the United States.