报告人：Prof. John Texter
School of Engineering Technology, Eastern Michigan University, Ypsilanti, MI 48197, USA
时 间：10月16日（周五）14: 30-15:30
Stimuli-responsiveness in polymer design is providing advanced materials that exhibit switchable porosity in membranes and coatings, switchable particle formation and thermodynamically stable nanoparticle dispersions, and switchable compatibility of nanomaterials in changing environments. Basic colloid and surface chemistry concepts are reviewed that lead to efficient dispersion and stabilization, and the ultimate approach is shown not to be matching of solvent and substrate (Gibbs) surface free energies but minimizing the solid-surface interfacial Gibbs free energy. We demonstrate the efficacy of two classes of stimuli-responsive polymers in stabilizing nearly complete exfoliation of graphene aggregates in water at concentrations up to 5% graphene by weight (surpassing previous attempts by two orders of magnitude) using recently developed triblock copolymers and copolymeric nanolatexes based on an ionic liquid acrylate surfactant. We also show that dilute and concentrated graphene dispersions are rheo-optical fluids, and we demonstrate stimuli-responsive phase transfer. A quantitative kinetic model for exfoliation is introduced that greatly aids the interpretation of polymeric-assisted exfoliation and stabilization, and that can be easily fitted to experimental exfoliation data. Some outstanding research problems are articulated.
John Texter is Professor of Polymer and Coating Technology at Eastern Michigan University. He has been Editor-in-Chief of the Journal of Dispersion Science and Technology, Associate Editor of the Journal of Nanoparticle Research, and Section Editor for Applications of Current Opinion in Colloid and Interface Science. He is an inventor, editor, and author of over 200 publications including five books, 46 issued U.S. patents, and numerous research and review articles. His research focuses on stimuli responsive polymers, particles, and materials and the general area of dispersion science and practice.