Session S17: Modeling of Polymers: Blocks, Networks and Solutions
2:30 PM–5:30 PM, Wednesday, March 7, 2007
Colorado Convention Center Room: 102
Sponsoring Units:
DPOLY DCOMP
Chair: Venkat Ganesan, University of Texas at Austin
Abstract ID: BAPS.2007.MAR.S17.12
Abstract: S17.00012 : Amorphous and crystalline states of ultrasoft colloids: A Molecular Dynamics study
4:42 PM–4:54 PM
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Abstract 
Authors:
A.N. Rissanou
M. Yiannourakou
I.G. Economou
(NCRPS, Demokritos)
D. Vlassopoulos
I.A. Bitsanis
(FORTH-IESL)
In dense suspensions of multi-arm star polymers a ``\textit{reversible thermal vitrification}'' was observed experimentally under ``marginal'' solvent conditions. We have investigated the origin of this phenomenon via MD simulations at the \textit{mesoscopic scale}$^{1,2,}.$ We reported the emergence of an amorphous solid state, upon heating of the ``soft spheres''. This transient glassy state resulted from star swelling, ``free volume'' deprivation and ``dynamical arrest'' of ``soft-spheres''. We monitored the ageing of the amorphous stage towards more crystalline FCC structures. The effects of size-dispersity and arm MW on crystallization were studied qualitatively. The overall picture revealed the existence of new ``dynamically arrested'' states, all of which could be termed ``crystalline'' but differed as to the ``degree of crystallinity''. Quantitative analysis of particle trajectories supplied mean square displacement curves which at the higher temperatures are typical of ``delayed'' Fickian diffusion. Even the aged crystalline states exhibited weak diffusion in contrast with the null diffusion of the crystals resulting from a FCC initial configuration. $^{1}$ Rissanou et al., \textit{Phys. Rev. E } \textbf{71} 011402-1~:12 (2005) $^{2}$ Rissanou et al., \textit{J. Chem. Phys. }\textbf{124} 044905-1~:11 (2006)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.S17.12