New Materials from Thermodynamically Stable Dispersions

报告题目:New Materials from Thermodynamically Stable Dispersions

  报告人:Prof. John Texter

    Eastern Michigan University, USA

  报告时间:2019年2月28日(星期四),下午13:30-14:30

  报告地点:苏州大学独墅湖校区912-509




Abstract:

Free-energy driven dispersion formation is of intense interest because microscopic to nanoscopic phase separation from macroscopic phases of chemical components involves an intriguing balance of chemical forces that results in apparent thermodynamic stability. We illustrate how stimuli-responsive block copolymers comprising polymerized ionic liquid (PIL) blocks can be prepared by modified emulsion polymerization methods and demonstrate reversible particle precipitation in the nano-scale range. We also report a single-pot condensation polymerization approach to synthesizing polyurethanes (PUs) in solvent, wherein aqueous compatibility is induced by using imidazolium hydroxide salts (ionic liquids) as chain terminating groups. Our creation of PUDs (polyurethane dispersions) are described with respect to spontaneous self-dispersing when such PUs are dried (of solvent) and placed in water. The accompanying size evolution of such dispersions is illustrated by videography and by dynamic light scattering, and size reduction from more strenuous activation by sonication is studied. Effects of indifferent salt on aqueous stability are measured, and anion-dependent stimuli-responsiveness is demonstrated and characterized. This stimuli-responsiveness appears based on tuning imidazolium-anion pair solubility. Film formation is also examined. Water-sensitive films with weak mechanical properties are obtained and appear promising for hydrogel delivery applications, and formulations combatting water sensitivity are demonstrated.

Solvent-free nanofluids obtained from organo-trialkoxysilanes on nanoparticle (core) templates and surface decorated with both ionic liquid organic salt groups and with various reactive groups are exotic cross-linking agents that define new types of resins. Such agents can be used to mitigate embrittlement provided by nanofillers while increasing toughness. We find that such materials can be used to produce thin films including UV protective clearcoats and an interesting new family of adhesives/sealants. Such materials also are reactive “inks” and provide building blocks for additive micron scale additive printing (manufacturing) and for designing new soft materials. We also show that auto-condensation of such organoalkoxysilanes without a templating core produces solvent-free nanofluids that exhibit classical liquid properties with some distinct differences. This system is the first experimental particle system reported that exhibits multiphase coexistence that otherwise is frustrated from crystallizing due to polydispersity.

  

CV

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 Current Opinion in Colloid and Interface Science, in which he has subsequently edited a special issue on Colloidal Graphene. He has worked for and consults through Strider Research Corporation, and he has worked for Eastman Kodak Company in various areas of dispersion and emulsion technology.  He received his undergraduate engineering education and his PhD in Chemistry from Lehigh University, where he studied at the Zettlemoyer Center for Surface and Coatings Research.  He is an experienced lecturer, organizer, and technical project manager.  He is an inventor, editor, and author of over 200 publications including five books, 47 issued US patents, and numerous research and review articles.  He has received numerous awards and honors and he has served as Chairman of the ACS Division of Colloid and Surface Chemistry, of the Chemistry at Interfaces Gordon Conference, of the Chemistry of Supramolecules and Assemblies Gordon Conference, and of many international symposia.  He has been a Guest Chair Professor at the School of Chemistry, Chemical Engineering, and Materials Science of Soochow University and has been a visiting professor at the Max Planck Institute for Colloids and Interfaces in Potsdam where he was a Max Planck Society Fellow, and at the Graduate School of Science and Technology, Kumamoto University. His research focuses on stimuli-responsive polymers, particles, and materials and the general area of dispersion science and practice

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