Professor Goran Ungar

Emeritus Professor Goran Ungar

Bsc PhD CPhys
Professor of Polymers and Organic Materials

Email: g.ungar@sheffield.ac.uk

Address: Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD

Research interests

Two main research areas: The first is the study of structure and phase behaviour of liquid crystalline (l.c.) and supramolecular polymeric 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 (LC) dendrimers andamphiphiles, soft quasicrystals, novel thermotropic l.c. phases with 2d and 3d periodicity ("micellar",bicontinuouscubic and non-cubic, columnar, honeycomb), controlled shape supramolecularnano-objects, helical self-assembly of organic semiconductors, LC-directed superlattices of metal and semiconductor nanoparticles for photonic and metamaterials, nano-confined LCs highly conducting polymer electrolytes.

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" crystallizationmechanisms has been proposed for flexible polymers. Furthermore, new layer structures and superlattices were discovered. New mathematical models allowed us to describe quantitatively the shapes of polymer crystals. We study structure and structure formation of biodegradable and light-emitting polymers, and investigate structure, morphology, and structure formation in semicrystalline polymers, including biodegradable polyesters and copolyesters, as well as in bulk and thin-film nanocomposites containing nanoparticles, nanofibres and graphene.

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. Low and wide angle scattering X-ray 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- and wide-angle scattering experiments are carried out at ESRF and Diamond synchrotronsand neutron diffraction at ISIS and ILL. Diffraction techniques are complemented with microscopies: optical, TEM, SEM and, in particular, high-resolution AFM. Much of the research is done in collaboration with Dr. X.B. Zeng.

Research themes/centres
Recent key projects
  • Project Leader of the SCALES network “Complexity across lengthscales in soft matter” funded by European Science Foundation.
  • European FP7 project “Self-Organized Nanomaterials for Tailored Optical and Electrical Properties - NANOGOLD”.
  • “Materials for Renewable Energy NaturE's Way (RENEW)” (PIRE scheme, NSF-EPSRC).
Professional activities and recognition
  • Invited speaker at over 80 international conferences
  • Visiting Professor at Universities of Hiroshima, Barcelona, Zhejiang Sci-Tech and Seoul National University
  • On Editorial Board of Polymer Journal
  • Member of the Committee of the British Liquid Crystal Society
  • Member of the Beam Allocation Panel of the UK Synchrotron Radiation Source
  • Member of the EPSRC College
  • Over 10,000 citations, h-index51
Key publications

Refereed articles in international journals or book chapters:

  • W. Stevenson, Z. Ahmed, X.B. Zeng, C. Welch, G. Ungar, G. Mehl, “Molecular organization in the twist-bend nematic phase by resonant X-ray scattering at the Se K-edge”, Arxiv 2016 arxiv.org/abs/1612.01180
  • G. Ungar, Z.H. Chen, X.B. Zeng “X-Ray Scattering”, Chapter in Liquid crystals with nano- and microparticles, ed. J. Lagerwall and G. Scalia, World Scientific, Singapore 2016 (ISBN: 9789814619257)
  • M.-S. Ho, B. E. Partridge, H.-J. Sun, D. Sahoo, P. Leowanawat, M. Peterca, R. Graf, H. W. Spiess, X. B. Zeng, G. Ungar, P. A. Heiney, C.-S. Hsu, V. Percec, “Screening Libraries of Semifluorinated Arylene Bisimides to Discover and Predict Thermodynamically Controlled Helical Crystallization”, ACS Combinatorial Sci., 2016 18 723-739 dx.doi.org/10.1021/acscombsci.6b00143
  • X. H. Yao, L. Cseh, X. B. Zeng, M. Xue, Y. S. Liu, G. Ungar, “Body-centred cubic packing of spheres – the ultimate thermotropic assembly mode for highly divergent dendrons” Nanoscale Horiz. 2016 (dx.doi.org/10.1039/c6nh00155f), Highlight: dx.doi.org/10.1039/C7NH90004J
  • X. B. Zeng, M. Prehm, G. Ungar, C. Tschierske, F. Liu “Formation of a Double Diamond Cubic Phase by Thermotropic Liquid Crystalline Self-assembly of Bundled Bolaamphiphiles” Angew. Chem. Int. Ed., 55(29):8324-8327 dx.doi.org/10.1002/ange.201602734
  • M.-H. Yen, J. Chaiprapa, X. B. Zeng, Y. Liu, L. Cseh, G. H. Mehl, G. Ungar “Added Alkane Allows Thermal Thinning of Supramolecular Columns by Forming Superlattice - An X-ray and Neutron Study” J. Am. Chem. Soc. 2016, 138, 5757–5760. dx.doi.org/10.1021/jacs.6b01172
  • S. L. Wang, H. Xu, X. Wu, P. Li, G. Ungar, Y. Liu, J. Shen, W. Tang, “Structural, Magnetic and Electrical Transport Properties of Double Perovskite Tb2MnCoO6” J. Mater. Res. 2016 dx.doi.org/10.1557/jmr.2016.112
  • X. Z. Cao, H. Merlitz, C. X. Wu, G. Ungar, J.-U. Sommer, “Theoretical Study of Dispersion-to-Aggregation of Nanoparticles in Adsorbing Polymers from Molecular Dynamics Simulation” Nanoscale 2016, 8, 6964-6968; dx.doi.org/10.1039/C5NR08576D
  • C. Roche, H-J Sun, P. Leowanawat, F. Araoka, B. E. Partridge, M. Peterca, D. A. Wilson, M. E. Prendergast, P. A. Heiney, R. Graf, H. W. Spiess, X. B. Zeng, G. Ungar, V. Percec, “A Supramolecular Double Helix that Disregards Chirality”, Nature Chemistry 2016, 8, 80-89. dx.doi.org/10.1038/nchem.2397
  • A. Miyazaki, M. Matsubara, X.B. Zeng, A. Muramatsu, G. Ungar, K. Kanie, “Rheology of Thermotropic Liquid-Crystalline Dendron-Modified Gold Nanoparticles”, Mol. Cryst. Liq. Cryst., 2015, 617, 50-57. dx.doi.org/10.1080/15421406.2015.1075818
  • C. Tschierske, G. Ungar “Mirror-Symmetry Breaking by Chirality Synchronization in Liquids and Liquid Crystals of Achiral Molecules”, ChemPhysChem 2016, 17, 9-26. (dx.doi.org/10.1002/cphc.201500601); Featured on front cover. Cover story.

Full publication list