Research Highlights

Transient Metal-Ligand Bond For Rapid Autonomous Self-Healing Polymers

In the Journal of the American Chemical Society, we report the use of multiphasic design developed in our lab to combine mechanical robustness with efficient self-healing. In this report, the naturally ubiquitous Zn2+ - imidazole coordination is incorporated in the amorphous soft phase as the dynamic motif responsible for self-healing. This state-of-the-art material fully repairs catastrophic damage in just three hours in ambient conditions while maintaining the high strength and toughness characteristic of our multiphasic design.

Direct Correlation Of Molecular And Bulk Mechanical Properties In Titin-Mimicking Polymer

Reported in Nature Materials, we demonstrate the use of atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) to quantitatively derive the energy landscape of modular rupture and refolding of our titin-mimicking polymer. This is the first example of a direct correlation between nano-mechanical properties and bulk mechanical performance using the energy landscape derived from SMFS. The report demonstrates the potential for SMFS to serve as a guide for rational design of advanced multifunctional materials.

Stiff & Autonomous Self-Healing Polymers

In a recent paper in Nature Chemistry, we report a general multiphase design of stiff polymers that can repair themselves without any external help from light, heat, healing agents, or solvents. The multiphase design is key to combine advanced mechanical properties of nanocomposites with autonomous self-healing capability of supramolecular assembly. The work is also highlighted recently in C&EN News.

Poly(Protein) with Exceptional Mechanical Stability

In a recent paper in the Proceedings of the National Academy of Sciences, Prof. Zhibin Guan and former student Dora Guzman in Chemistry, with collaborators Prof. Pierre Baldi and Arlo Randall in the School of Information and Computer Sciences, reported a poly(protein) with exceptional mechanical stability. The protein discovery and mechanistic understanding were achieved through a combination of bioinformatics search, computation, protein engineering, and single molecule force spectroscopic studies.

A Biomimetic Modular Polymer with Tough and Adaptive Properties

In a recent Communication to the Journal of the American Chemical Society , Professor Zhibin Guan, graduate students Aaron Kushner and Gregory Williams, and undergraduate student John Vossler, reported the first synthetic polymer to possess the advanced mechanical properties found in many natural materials, including good resistance to deformation, high toughness, and adaptive properties such as shape memory. Inspired by skeletal muscle protein titin , this biomimetic modular polymer has many possible applications, including implants, prosthetics, and "smart" materials. This work is highlighted in Nature Chemistry and Chemical and Engineering News .

Click to fold: Cycloaddition-Induced Folding of a Polymer into beta-Sheets

A recent communication to the Angew. Chem. from the Guan group was selected by the editors as a hot paper. In this communication, graduate student Ting-Bin Yu, research associate Jane Z. Bai, and Prof. Zhibin Guan reported the first example of polymerization-induced folding of a polymer into extensive beta-sheets. Cu(I)-catalyzed azide-alkyne cycloaddition polymerization of a peptide monomer induced folding of the resultant polymer into well-defined beta-sheets, which further self-assemble into hierarchical nanofibrils. The Guan group is currently applying this methodology to the synthesis of polymers mimicking spider dragline silk, one of the strongest natural fiber that contains extensive beta-sheets.

Novel Cyclophane Catalyst for Valuable Materials

A "Holy Grail" in olefin polymerization catalysis field is to discover transition metal catalysts that can efficiently copolymerize polar olefins. In a Communication to J. Amer. Chem. Soc. that is currently in press, Professor Guan and his graduate student Chris Popeney, and former postdoctoral fellow Drexel Camacho, have reported a cyclophane-based Pd(II) complex that is highly efficient in incorporating polar olefins like acrylates. Furthermore, low temperature NMR studies have revealed a unique mechanistic origin for the increased efficiency for polar olefin incorporation.

Hybrid Sugar-Peptide Copolymers

Saccharide-peptide hybrid copolymers as highly functional biomaterials, is the new design concept introduced by Professor Zhibin Guan , published online September 15, in Angewandte Chemie International Edition . The novelty of the demonstrated concept, and its promise as a flexible approach for the synthesis of biomaterials with tailored properties has already been recognized in Chemical Engineering News (C&EN) and the international press.