Professor Goran Ungar
Bsc PhD CPhys
Professor of Polymers and Organic Materials
Address:
Department of Materials Science and Engineering
Sir Robert Hadfield Building
Mappin Street, Sheffield, S1 3JD
Telephone: +44 (0) 114 222 5457
Fax: +44 (0) 114 222 5943
Email: g.ungar@sheffield.ac.uk
Research interests
Two main research areas: The first area is the study of structure and phase behaviour of liquid crystalline (l.c.) and supramolecular polymeric, oligomeric and low molecular systems. Molecular organisation is investigated by diffraction, microscopy and spectroscopy. Applying principles of self-assembly, new molecular architectures are designed and tested in collaboration with synthetic chemists. Current topics include molecular channel matrices, liquid crystalline dendrimers and amphiphiles, novel thermotropic l.c. phases with 3-d periodicity ("micellar" and bicontinuous cubic and non-cubic), controlled shape supramolecular nano-objects, helical supramolecular self-assembly, highly conducting polymer electrolytes (with Prof. Wright).
The second area of research is structure and morphology of semicrystalline polymers. In particular, monodisperse model polymers in the form of very long n-alkanes are studied. As a result of these studies the "self-poisoning" crystallization mechanisms has been proposed for flexible polymers. Furthermore, new layer structures and superlattices were discovered. Recently new mathematical models allowed us to describe quantitatively previously poorly understood shapes of polymer crystals. We study structure and structure formation of biodegradable and light-emitting polymers.
Potential applications of the research on l.c. and supramolecular systems, including molecular electronics, photonic bandgap crystals, controlled release agents, l.c. displays and speciality fibres.
The development of advanced instrumentation and analytical methods for x-ray and neutron scattering, specifically tailored for liquid crystal and polymer studies, plays a major part in the group's research. Quadrant and Image Plate low and wide angle scattering detectors are incorporated into purpose-built in-house equipment. Synchrotron experiments are carried out where high source brilliance and high resolution are required. Grazing-incidence small-angle scattering (GISAXS) setups have been established in collaboration with Cardiff University at ESRF and Diamond synchrotron laboratories. Fast real-time small-angle neutron scattering (RTSANS) has been developed in collaboration with ISIS for in situ studies of crystallization of polymers and other materials on the 1-10 s timescale.
Key projects
- Project Leader of the SCALES network (“Complexity across lengthscales in soft matter”) funded by the SONS Programme of the European Science Foundation involving 6 institutions in 4 EU countries.
Professional activities and recognition
- Member of the Committee of the British Liquid Crystal Society
- Member of the Beam Allocation Panel of the UK Synchrotron Radiation Source
- Member of Management Committee of the Self-Organized Nanostructures Programme of the European Science Foundation
- Former member of the EPSRC Structural Materials College
- Invited speaker at 50 international conferences
- h-factor 47
Key publications
- G. Ungar, J. Stejny, A. Keller, I. Bidd, M.C. Whiting, The crystallization of ultralong normal paraffins: the onset of chain folding, Science, 229, 386, (1985).
- S.D. Hudson, H-T. Jung, V. Percec, W-D. Cho, G. Johansson, G. Ungar and V.S.K. Balagurusamy, Direct visualization of individual cylindrical and spherical supramolecular dendrimers, Science, 278, 449, (1997).
- V. Percec, C-H. Ahn, G. Ungar, D.J.P. Yeardley, M. Möller and S.S. Sheiko, Spherical and cylindrical supermolecules from polymer backbones jacketed with quasi-equivalent dendritic coats, Nature, 391, 161, (1998).
- G. Ungar, Y. Liu, X.B. Zeng, V. Percec and W-D. Cho, Giant supramolecular liquid crystal lattice, Science, 299, 1208, (2003).
- X.B. Zeng, Y. Liu, G. Ungar, V. Percec, A.E. Dulcey, J.K. Hobbs, Supramolecular Dendritic Liquid Quasicrystals, Nature, 428, 157-160, (2004).
- X.B. Zeng, G. Ungar, M. Impéror-Clerc, A Triple-Network Tricontinuous Cubic Liquid Crystal, Nature Materials, 4, 562-567, (2005).
Research group
Postdoctoral:
Dr. Maxim A. Shcherbina
Doctoral:
Mr. Fangning Xie
Mr. Jitrin Chaiprapa
Mr. Feng Liu (co-supervisor, with Dr. X. Zeng)
Miss Christa Weber (co-supervisor, with Dr. J. Hobbs)
Research themes/centres
Polymers, Liquid Crystals and Supramolecular Structures Group