We intend to develop innovative synthetic techniques for high value-added nanomaterials. We conduct the research via fundamental exploration into newly emerged supramolecular chemistry. Particularly, our research takes advantage of well developed organometallic and polymer chemistry in an attempt to incorporate the properties of metal elements (catalytic, magnetic, electronic etc.) and macromolecules (mechanical, processible) into functional nanomaterials. Our effort has made a number of breakthroughs in synthetic techniques, including Migration Insertion Polymerization (MIP), Miniemulsion Periphery Polymerization (MEPP) and Living Self-Assembly (LSA). We are currently exploring functional nanomaterials using the concepts and techniques developed in the group.
- Migration Insertion Polymerization (MIP)
- Miniemulsion Periphery Polymerization (MEPP)
- Living Self-Assembly (LSA)
Migration Insertion Polymerization (MIP)
Metal-Containing Polymer (MCP) is a developing research field side by side with supramolecular chemistry. Meanwhile, MCPs, due to the presence of metal complex, is an attractive component for self-assembled functional nanomaterials. Synthesis of main-chain MCPs, where metal elements involve in the construction of polymer backbones, is particularly challenging. Only a few types of polymers, such as Polyferrocenylsilane (PFS), have been well studied. We have creatively developed Migration Insertion Polymerization (MIP), through which metal elements are incorporated into the backbone of polymer chains. As shown in the Scheme, MIP of cyclopentadienyldicarbonyldiphe-nylphosphinopropyliron (FpP) results in air stable polycyclopentadienylcarbonyldiphenylphosphinobutanoyliron (PFpP) with its main chain constructed from both P-Fe metal coordination and Fe-C metal-carbon bonds. Further developing, extending the scope of MIP and material exploration of the resulting polymers are the major concern of our current research.
References
- Wang, X. S.; Cao, K.; Liu, Y. B.; Tsang B, Liew S. Migration Insertion Polymerization (MIP) of cyclopentadienyldicarbonyldiphenylphosphinopropyliron (FpP): a new concept for main chain Metal-Containing Polymers (MCPs), J. Am. Chem. Soc. 2013, 135, 3399-3402.
- Kai Cao, Brian Tsang, Yibo Liu, Daniel Chelladural, William P. Power, and Xiaosong Wang Synthesis, Cyclization and Migration Insertion Polymerization of Cyclopentadienyldicarbonyldiphenylphosphinopropyl iron (FpP) in Solution Organometallics 2013
Miniemulsion Periphery Polymerization (MEPP)
We created MEPP polymerization technique in 2009 as an effort of our research into designed synthesis of functional nanoshells. The technique involves miniemulsion of amphiphilic molecules bearing polymerizable end groups, and subsequent polymerization at the periphery of the emulsion droplets. We have demonstrated that the technique is amendable for precise metal-coordination nanostructure design in terms of chemical composition, shapes and sizes (see images). We are interested to use this technique to develop functional nanomaterials for commercialization.
TEM images for Prussian blue metal coordination nanoshells: (a and b) spheres with varied size, (c) nanoboxes, (d) shells with conducting polymer (PPy) encapsulated and (e) confocal microscopy image shows photoluminescent properties of the core/shell particles in cells. All the particles were prepared via MEPP under varied conditions using EPE-Fe as surfactants.
(EPE-Fe: poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) terminated with pentacyano(4-(dimethylamino)pyridine)ferrate).
References
- Liang, G. D.; Xu, J. T.; Wang, X. S. Synthesis and characterization of organometallic coordination polymer nanoshells of Prussian blue using Miniemulsion Periphery Polymerization (MEPP), J. Am. Chem. Soc. 2009, 131 (15), 5378–5379.
- R. McHale, N. Ghasdian, Y. Liu, M. B. Ward, N. S. Hondow, H. Wang, Y. Miao, R. Brydson, X. S. Wang Synthesis of Prussian Blue Coordination Polymer Nanocubes via Confinement of the Polymerization Field using Miniemulsion Periphery Polymerization (MEPP), Macromol. Rapid Commun.2010, 31, 856-860.
- McHale, R.; Ghasdian, N.; Liu, Y. B.; Ward, M. B.; Hondow, N. S.; Brydson, R.; Wang, X. S. Prussian Blue Coordination Polymer Nanobox Synthesis using Miniemulsion Periphery Polymerization (MEPP), Chem. Commun. 2010, 46, 4574-4576.
- McHale, R.; Ghasdian, N.; Hondow, N. S.; Richardson, P. M. Voice, A. M.; Brydson, R.; Wang, X. S. Organosilica Nanoshells with Thin Crosslink by Miniemulsion Periphery Polymerization, Macromolecules, 2010, 43, 6343–6347.
- Ye S. J.; Liu, Y. B.; McHale, R.; Ghasdian, N.; Lu, Y.; Wang, X. S Photoluminescent Properties of Prussian Blue (PB) Nanoshells and PolyPyrrole (PPy)/PB Core/Shell Nanoparticles Prepared via Miniemulsion (Periphery) Polymerization, Chem. Commun. 2011, 47, 6831-6833.
Living Self-Assembly (LSA)
It was not until 2007, we, together with Prof. Manners and Prof. Winnik, developed Living Self-Assembly for precise synthesis of micelles. Consequently micelle architecture can be designed. This work has initiated unprecedented studies into designed supramolecular assemblies.
References
Wang, X. S.; Guerin, G.; Wang, H.; Wang, Y. S.; Manners, I.; Winnik, M. A. Formation of cylindrical block copolymer micelles and co-micelles of controlled length and architecture, Science 2007, 317, 644-647.