Lecture: Functional and Responsive Macromolecular Brush Materials
Lecturer: Bin Zhao, Professor, Department of Chemistry, University of Tennessee Knoxville
Date: June 9
Time: 15：00
Place: Academic hall, 3rd Floor, Lihua Building
Abstract of the lecture:
Linear polymer chains densely tethered by one end to a solid substrate or a polymer backbone are intriguing polymer systems, with the former being commonly called polymer brushes and the latter being descriptively termed molecular bottlebrushes. In all these systems, the grafted polymer chains are highly stretched, exhibiting unique structures and properties. In this talk, I will present two types of macromolecular brush materials: oil-soluble polymer brush-grafted nanoparticles (hairy NPs) as engine lubricant additives and stimuli-responsive shape-changing binary molecular bottlebrushes. While NPs have been viewed as potentially effective additives for lubricants for friction and wear reduction, further development is hindered by their dispersability and long-term stability in oils. By growing oil-soluble polymer brushes from NPs viasurface-initiated polymerization, we have shown that such hairy NPs exhibit excellent dispersability and superior stability in polyalphaolefin (PAO), the base oil for engine lubricants. With addition of 1 wt% hairy NPs into PAO, significant reductions in friction coefficient (up to ~ 40%) and wear volume (up to ~ 90%) are achieved. In the second part of the talk, I will present our recent work on stimuli-responsive molecular bottlebrushes. A “grafting to” method via “click” reaction has been developed to synthesize molecular brushes; the modular nature and the high grafting efficiency of this method allow for synthesis of heterografted molecular brushes with two or more distinct side chain polymers and facile tuning of the molar ratio of different side chain polymers. We show that thermosensitive binary heterografted molecular brushes undergo shape changing between worm-like and collapsed yet stable globular conformations upon temperature changes, which is utilized to control interactions between brushes and environment.
Introduction to Bin Zhao:
2013~ , Full professor, Department of Chemistry, University of Tennessee Knoxville.
2008-2012, Associate professor, Department of Chemistry, University of Tennessee Knoxville;
2002~2007, Assistant professor, Department of Chemistry, University of Tennessee Knoxville;
2000-2002, Postdoctoral research on microfluidics, University of Illinois at Urbana-Champaign;
2000, Ph.D. degree in polymer science, University of Akron;
1995, M.S. in polymer chemistry, University of Science and Technology of China;
1992, B.S. in polymer chemistry, University of Science and Technology of China;
His research interests include multicomponent polymer brushes, hairy particles, stimuli-responsive block copolymers and shape-changing molecular bottlebrushes, interfacial lubrication and adhesion.
He received Chancellor’s Award for Professional Promise in Research and Creative Achievement in 2010 and Paul and Wilma Ziegler Professorship from the University of Tennessee Knoxville, and Polymer Science Distinguished Alumni Award from the University of Akron in 2013. He was a member of Editorial Advisory Board of ACS journal Macromolecules (01/2009 – 12/2011).