Department of Materials Science and Engineering

The goal of current research in the Wiesner group is to combine knowledge about the self-assembly of soft polymeric materials with the functionality of solid-state materials to generate novel hierarchical and multifunctional hybrid materials. Research results of the group on the use of blocked copolymers as structure directing agents for inorganic materials suggest that in analogy to biology, the sequence information of higher order blocked synthetic macromolecular architectures may be used to encode information about hierarchical structure of co-assemblies with ceramic or other materials. These principles may permit the design of entirely new classes of functional materials that have no analogue in the natural world with potential applications ranging from power generation and energy conversion all the way to the life sciences.

As a particular model system to understand structure formation principles, silica-based hybrids from block copolymer mesophases have been studied extensively over the last ten years. One of the main working principles involves utilizing the thermodynamics of amphiphilic block copolymers, i.e., knowledge about their self-assembly behavior (bottom-up) to structure direct precursors for silica-type oxides. In the meantime these principles have been extended to other oxides as well as to non-oxide ceramics (e.g., SiCN). Synthesis results in mesostructured hybrid materials with structure control down to the nanometer length scale that upon, e.g., thermal processing can subsequently be converted into purely ceramic materials with preserved structure (e.g., mesoporous materials). The final materials have a broad range of potential applications in, e.g., catalysis and separation.

A second major current research direction of the Wiesner group focuses on a novel class of fluorescent core-shell silica nanoparticles, now referred to as C-dots, with potential applications, e.g., as fluorescent labels in biolabeling and bioimaging. Water-soluble C- dots encapsulate multiple organic fluorophores into a solid-state silica environment, thereby improving their photophysical properties as compared to the free dye in water. C-dots have narrow size distributions and in the 20-30 nm size range achieve brightness levels reaching those of semiconductor quantum (Q-) dots with simultaneously enhanced photostability over free dye in aqueous solutions. They are synthesized through a modified Stöber process and overcome toxicity and disposal issues of competing Q-dot technologies. As a result of their optical property profiles they constitute an attractive alternative to existing materials platforms for applications in information technologies and the life sciences requiring bright fluorescent probes. Fundamental studies are aimed at understanding and controlling optical phenomena of this novel class of radiative nanoparticles and of optical structures and devices that integrate them.

Some of the research projects that are currently pursued in the group include:

1. formation mechanisms of nanostructured polymer-inorganic hybrid materials from diblock- and triblock-copolymers and nanoparticles
2. mesoporous oxides and non-oxides for power generation and energy conversion
3. novel dendron derived structure directing agents for functional materials
4. nanostructured block copolymer-silica hybrid thin films
5. synthesis and characterization of C dots from various organic fluorophores
6. preparation of multifunctional C dots
7. C dots as labels and probes in bioimaging
8. locomotive motion in hydrogels from symmetry breaking of gel volume phase transitions

1. S. C. Warren, F. J. DiSalvo, U. Wiesner, Nanoparticle-tuned assembly and disassembly of mesostructured silica, Nature Mater. 6 (2007), 156-161.
2. S. C. Warren, M. J. Banholzer, L. S. Slaughter, E.P. Giannelis, F. J. DiSalvo, U. Wiesner, Generalized Route to Metal Nanoparticles with Liquid Behavior, J. Am. Chem. Soc. 128 (2006), 12074-12075.
3. A. Burns, H. Ow, U. Wiesner, Fluorescent Core-Shell Silica Nanoparticles: Towards “Lab on a Particle” Architectures for Nanobiotechnology, Chem. Soc. Rev. 35 (2006), 1028-1042.
4. L. Yeghiazarian, S. Mahajan, C. Montemagno, C. Cohen, U. Wiesner, Directed Motion and Cargo Transport Through Propagation of Polymer Gel Volume Phase transitions, Adv. Mater. 17 (2005), 1869-1873.
5. H. Ow, D. R. Larson, M. Srivastava, B. A. Baird, W. W. Webb, U. Wiesner, Bright and Stable Core-Shell Fluorescent Silica Nanoparticles, Nanoletters 5 (2005), 113-117.
6. A. Jain, G. E. S. Toombes, L. M. Hall, S. Mahajan, C. B. W. Garcia, W. Probst, S. M. Gruner, U. Wiesner, Direct Access to Bicontinuous skeletal Inorganic Plumber’s Nightmare networks from block copolymers, Angew. Chem. Int. Ed. 44 (2005), 1226-1229.
7. B. M. Kamperman, C. B. W. Garcia, P. Du, H. Ow, U. Wiesner, Ordered Mesoporous Ceramics Stable up to 1500°C from Diblock Copolymers, J. Am. Chem. Soc. 126 (2004), 14708-14709.
8. B.-K. Cho, A. Jain, S. M. Gruner, U. Wiesner, Mesophase Structure-Mechanical and Ionic Transport Correlations in Extended Amphiphilic Dendrons, Science 305 (2004), 1598-1601.
9. K. Cho, A. Jain, S. Mahajan, H. Ow, Sol M. Gruner, U. Wiesner, Nano-Hybrids from Liquid Crystalline Extended Amphiphilic Dendrimers, J. Am. Chem. Soc. 126 (2004), 4070-4071.
10. P. Du, M. Li, K. Douki, X. Li, C. B. W. Garcia, A. Jain, D.-M. Smilgies, L. J. Fetters, Sol M. Gruner, U. Wiesner, C. K. Ober, Additive-driven Phase Selective Chemistry in Block Copolymer Thin Films: The Convergence of Top-Down and Bottom-Up Approaches, Adv. Mater. 16 (2004), 953-957.
11. A. C. Finnefrock, R. Ulrich, G. E. S. Toombes, S. M. Gruner, Ulrich Wiesner, The Plumber’s Nightmare: A New Morphology in Block Copolymer-Ceramic Nanocomposites and Mesoporous Aluminosilicates, J. Am. Chem. Soc., 125 (2003), 13084-13093.
12. C. B. W. Carcia, Y. Zhang, F. DiSalvo, U. Wiesner, Mesoporous Aluminosilicate Materials with Superparamagnetic γ-Fe2O3 Particles Embedded in the Walls, Angew. Chem. Int. Ed. 42, (2003), 1526 – 1530.
13. P. F. W. Simon, R. Ulrich, H. W. Spiess, U. Wiesner, Review: Block copolymer – ceramic hybrid materials from organically modified silicon precursors, Chem. Mater. 13 (2001), 3464-3486.
14. G. Floudas, B. Vazaiou, F. Schipper, R. Ulrich, U. Wiesner, H. Iatrou, N. Hadjichristidis, Poly(ethylene oxide-b-isoprene) Diblock Copolymer Phase Diagram, Macromolecules 34 (2001), 2947-2957.
15. S. M. De Paul, J. W. Zwanziger, R. Ulrich, U. Wiesner, H. W. Spiess, Structure, Mobility, and Interface Characterization of Self-Organized Organic-Inorganic Hybrid Materials by Solid-State NMR, J. Am. Chem. Soc. 121 (1999) 5727-5736.
16. R. Ulrich, A. Du Chesne, M. Templin, U. Wiesner, Nano-objects with controlled shape, size and composition from block copolymer mesophases, Adv. Mater. 11 (1999), 141-146.
17. M. Templin, A. Franck, A. Du Chesne, H. Leist, Y. Zhang, R. Ulrich, V. Schädler, U. Wiesner, Organically Modified Aluminosilicate Mesostructures from Block Copolymer Phases, Science 278 (1997), 1795-1798.
18. M. Templin, U. Wiesner, H. W. Spiess, Multinuclear Solid-State-NMR studies of Hybrid Organic-Inorganic Materials, Advanced Materials 9 (1997), 814-817.
19. Y. Zhang, U. Wiesner, H. W. Spiess, Frequency Dependence of Orientation in Dynamically Sheared Diblock Copolymers, Macromolecules 28 (1995), 778 – 781.
20. U. Wiesner, N. Reynolds, C. Boeffel, H. W. Spiess, Photoinduced reorientation in liquid-crystalline polymers below the glass transition temperature studied by time-dependent infrared spectroscopy, Makromol. Chem., Rapid Commun. 12 (1991), 457 – 464.

• 2006-2007: One-year sabbatical, Physics Cavendish Labs, Cambridge University, UK.
• Since 2005: Full Professor, MS&E, Cornell University, Ithaca, New York
• 2003: Co-founder of Hybrid Silica Technologies, Inc., Ithaca, New York
• 2001-Present: Affiliation to the Max-Planck-Institute for Polymer Research, Mainz, Germany
• 1999-Present: Associate Professor, MS&E, Cornell University, Ithaca, New York
• 1998-1999: Tenured Staff, Max-Planck-Institute for Polymer Research, Mainz, Germany
• 1993-1998: Scientific Assistant, Max-Planck-Institute for Polymer Research, Mainz, Germany
• 1991-1993: Postdoctoral Associate, Laboratoire de Physicochimie Structurale et Macromoléculaire, associé au CNRS, ESPCI, Paris, France
• 1998: Habilitation Phys. Chem., Dept. Chemistry & Pharmacy, Mainz University, and Max-Planck-Institute for Polymer Research, Mainz
• 1991: Ph.D. Phys. Chem., Max-Planck-Institute for Polymer Research, Mainz;
• 1988: Diploma Chemistry, Johannes Gutenberg University of Mainz, Germany
• 1982-1988 Chemistry Studies University of Mainz, Germany, & UC Irvine, CA.