We address the issue of topological interactions in blends of ring-linear polyethylene oxide (PEO) melts with a focus on cyclic threading by linear molecules.1,2 Our approach entails three main steps. First, detailed molecular dynamics (MD) simulations are performed with model PEO melts characterized by molecular weights M up to 20,000 g/mole for times up to one microsecond to get a large number of fully equilibrated atomistic configurations at the conditions of interest (P=1atm and T=413K). Second, the accumulated trajectories are reduced to ensembles of primitive paths (PPs) by applying the so called CReTA algorithm (Contour Reduction Topological Analysis)2 for the static analysis of uncrossability constraints in linear polymer systems; the method is adapted here to the case of ring polymers presenting no chain ends. Third, we geometrically analyze the reduced ensemble of PPs using vector calculus to identify ring-ring and ring-linear threading events and compute their characteristic time scales. We will present numerical results for: a) the relationship between the percentage of rings chains that are threaded by other rings or linear chains and degree of contamination of the melt in linear chains, b) the characteristic survival times of the two types of threadings (ring-ring and ring-linear), and c) their effect on individual ring molecule dynamics and conformational properties. It turns out that, in particular, ring threading by linear molecules is so strong that it leads to a dramatic reduction of ring diffusivity and orientational relaxation rendering the system’s overall dynamics highly heterogeneous. The conformational properties, on the other hand, remain practically unaffected. 1. Tsalikis, D. G.; Mavrantzas, V. G. ACS Macro Lett. 2014, 3, 763-766. 2. Tsalikis, C.; Koukoulas, T.; Mavrantzas, V.G. React. Funct. Polym. 2014, 80, 61-70. 3. Tzoumanekas, C.; Theodorou, D.N. Macromolecules 2006, 39, 4592-4604.

Threading of ring poly(ethylene oxide) molecules by linear chains or other rings in the melt: molecular dynamics simulations followed by a geometric analysis

249th National Meeting (2015)

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