Viscosity of Ring Polymer Melts

Abstract

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as function of the number of entanglements Z. In the unentangled regime η0,linear/η0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/η0,ring=2. In the entanglement regime, the Z-dependence of rings viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1<Z<20, η0,linear/η0,ring~ Z1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring~ Z1.6±0.3) and the simulations (η0,linear/η0,ring~ Z2.0±0.3). Nevertheless, the present collection of state-of-the- art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year old problem.

A topologically driven glass in ring polymers

“…This is the reason why an entanglement plateau is absent. It also means that the slowing down of the dynamics in systems of rings might not be clearly captured by the stress relaxation function GðtÞ frequently studied in the literature (6)(7)(8)30), which is mostly dominated by the unconstrained internal modes, but rather by the mean square displacement of the unfrozen rings (as in Fig. 4) or the dynamic scattering function S c ðq, tÞ.…”

“…In contrast, ring polymers possess a closed contour, which leads to markedly different relaxation and diffusion mechanisms. Recently, there has been much improvement in the production of purified systems of rings (6)(7)(8), with the consequent result that more and more experimental puzzling evidence requires a deeper understanding of their motion in concentrated solutions and melts from a theoretical point of view.…”

Single-Molecule Imaging Reveals Topology Dependent Mutual Relaxation of Polymer Chains

“…16 The motion of the chains in linear-cyclic blends has been reported to be even more complicated. 17,18 Despite decades of experimental [19][20][21][22][23] and simulation studies, 24-27 the motion of entangled cyclic polymers remains controversial because the concept and the role of the entanglement between the cyclic polymers has not been clarified. 28 This is partly due to the lack of a method that can directly characterize the motion of individual polymer chains in an entangled melt and solution under equilibrium conditions.…”

Topological Interactions in Ring Polymers

“…Ring polymers have, in some sense, a greater freedom of movement with respect to their linear or quenched branched polymers, although they suffer of much stronger topological constraints due to the fact that they have to preserve their topological state at all times. Because of all this, ring polymers in solution are, at present, a topic of intense debate and lively interest among the Polymer Physics community [Kapnistos et al, 2008, Halverson et al, 2011a, Mirny, 2011, Pasquino et al, 2013, Rosa and Everaers, 2014, Grosberg, 2014.…”

“…system has received much attention in the last years are twofold: firstly, it has been found to share some properties with the organisation of chromosomes inside the cell nucleus [Cremer and Cremer, 2001, Rosa and Everaers, 2008, Vettorel et al, 2009, Mirny, 2011, Halverson et al, 2011a, Halverson et al, 2011b, Grosberg, 2014, Rosa and Everaers, 2014, Halverson et al, 2014, and secondly, recent experimental advances allowed, for the first time, its purification from linear contaminants which allowed us to study directly the pure melt of rings using artificial polymers such as polyisoprene or polystyrene chains [Kapnistos et al, 2008, Pasquino et al, 2013.…”