RINGEFF · Effective Interactions and correlations of ring polymers

Effective Interactions and correlations of ring polymers

Within the RINGEFF-project, we obtained Veff(r) for different microscopic potentials (HS, LJ, LJ-24,6), polymer sizes (20-2000 monomers) and several topologies: Linear, ring, trefoil 31, and 51 topologies. We have thus been able to show that topology is a very important feature in polymer physics, at mesoscopic length scales (Rg) and at dilute/semi-dilute regimes, see figure 1.2. The feature observed in Veff(r) is independent of the microscopic potentials (microscopic details) that we considered. The Veff(r) calculated are valid up to the ring overlap concentration, see "A. Narros, A. J. Moreno, and C. N. Likos, Soft Matter 6, 2435 (2010)" for more details. To extent the range of validity of coarse-graining, we also have increased the level of detail on this approximation applying the “blob” picture. In this framework, we have performed simulations with “soft potentials” preventing crosslinking, and obtained similar results with those from full monomeric resolution. This was the main goal in this project, since it reduces enormously the computational effort and, at the same time, include the ingredient of the topology in simulations. A key deliverable/achievement was the creation of a new algorithm to prevent crossing since we are dealing with “soft potentials”, in which conservation of topology be satisfied. In addition, during this project a very detailed analysis of the polymer shape was performed, to clarify the mass distribution of the polymer and to rationalize our results by treating rings as interpenetrating ellipsoids. Finally, in RINGEFF we were able to analyze the interplay between topology and the solvent quality. This is a well known feature on linear chains but unexplored to-date with other topologies as ring, trefoil and 51 polymers. In this framework, we discovered that the more complicate is the topology, the lower the temperature at which the polymer achieves Gaussian statistics. The RINGEFF project results could be applied in many fields of biology, medicine and new material design. They bring forward the ingredient of topology as an important property to take into account in, for example, DNA studies, knotted proteins and enzymology of DNA replication. In addition, the project put forward novel coarsegraining techniques with topology to simulate bigger scale systems, those necessary to design and studying of biology and medicine. Thereby, the benefits of this project could include many parts of the society, since biology and new materials science are two fundamental basis of the technological society of nowadays. At the same time, EU research have an step forward in a very unexplored field of polymers with topological constraints.

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