1. Dynamics in Soft Materials
Group of Dr. Sokolov
Dynamics in Soft Materials UT
ORNL

2. Soft Matter Polymers Liquid Crystals Glass-forming Systems Colloids
Foams and Gels
Biological Systems

3. Dynamics is the Key to many Macroscopic Properties of Soft Materials
Characteristics of Soft Materials:
Variety of states and large degrees of freedom, metastable states;
Delicate balance between Entropic and Enthalpic contributions to the Free Energy;
Large thermal fluctuations and high sensitivity to external conditions;
Macroscopic softness.
Soft Matter Physics:
Extremely high complexity of the systems and of the physical phenomena
Traditional approximations often fail
Mostly phenomenological level, qualitative considerations
Many assumptions, some of them are not justified
Dynamics is the Key to many Macroscopic Properties of Soft Materials

4. Main directions of research in our group
Polymer Dynamics, Glass Transition
Dynamics and Function of Biopolymers
DNA Protein Lysozyme RNA
Nanostructured and Nanocomposite
Materials
Nano-Photonics, Plasmonics

5. Main Experimental Techniques
Light scattering: Raman and Brillouin scattering spectroscopy, plus dynamic light scattering cover the frequency range from mHz up to ~100 THz (corresponding time scales from hours to femtoseconds ).
Dielectric relaxation spectroscopy covers frequency range from mHz up to ~50 GHz.
Neutron scattering: use of SNS facilities at ORNL, NIST facilities, and also facilities in Europe. Although frequency range in that case is more limited (from MHz to ~100 THz), neutron scattering provides detailed microscopic information.
Optical microscopy combined with spectroscopy (Raman, fluorescence, etc.):
- confocal with lateral resolution ~0.5 mm;
apertureless near-field microscopy with ~20 nm lateral resolution.

6. Collaborations USA International
NIST Polymer Division IA&E Russ.Ac.Sciences Russia
Center for Neutron Research Bayreuth University Germany
AFRL Research Center Juelich Germany
NRL University Paris Sud France
ORNL ILL & ESRF, Grenoble France
Johns Hopkins University Chalmers Univ.of Technology Sweden
University of Maryland Universita di Messina Italy
Kent State University Universita ‘La Sapienza’ Italy
Bridgestone/Firestone University of Oxford UK
Lubrizol Horiba JY France
Silesian University Poland

7. Main Philosophy in our Group
After one year in my group I expect from a graduate student:
Independence in your research, I’m just an advisor
Even “wrong” ideas are better than no ideas at all
You propose what should we do (not me telling you what to do)
Team work
Presentation of results is very important part of your work; every student gives presentations a few times per year on the group meetings; good students attend national and international meetings
You are writing papers, I’m just helping and teaching you how to write and how to deal with referees

8. Polymer Dynamics, Glass Transition
The main goal is fundamental understanding of molecular motion and its relationship to macroscopic properties of polymeric and other glass forming materials.
We study, among other questions:
Glass transition; Cooperativity in molecular motions; Role of dynamic heterogeneities
Temperature variations of viscoelastic and mechanical properties, Decoupling phenomena in dynamics …
As an example:
Our recent finding – universality of chain relaxation behavior for many polymers when presented vs Tg/T [PRL 102, (2009); Macromolecules 39, 3322 (2006)].
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9. Dynamics and Functions of Biopolymers
The main goal is fundamental understanding of dynamics in proteins, RNA and DNA, and relationship between molecular motion and functions of biological macromolecules.
Recent finding:
We unravel the nature of the dynamic transition in biological macromolecules [Phys.Rev.Lett. 100, (2008); J.Chem. Phys. 128, (2008)].
Understanding the influence of solvents on protein dynamics, activity and stability is another goal of our research.
It is important for preservation of protein based products (pharmaceuticals, vaccines, food additives), cells and tissues. We designed a formulation where proteins can be preserved at room temperature up to ~10 years!!!
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10. VT1.45±0.1 km/s Nano-composite and Nano-structured Materials
Mechanical Properties of Viruses
Localized mode provides estimate:
Sub-monolayer WIV
500nm
VT1.45±0.1 km/s
Propagating and localized modes provide consistent estimates of the elastic constants. Virus appears to be stiffer than hard plastics
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Phys.Rev.E 78, (2008)

11. Nano-optics, Plasmonics
Enhanced field
Near-field ~10 nm
Plasmon particle
Laser beam
AFM tip
Laser spot ~1 mm
Far-field
We are developing:
Apertureless near-field optics based on local enhancement of optical signals in the vicinity of plasmon particles (e.g. Ag, Au).
Chemical mapping with ~20 nm lateral resolution
Topography
Raman
180nm
0nm
60nm
2000nm
1200
Topography
Raman
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