title: 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 meltsη0,linearto their ring counterpartsη0,ringat isofrictional conditions is discussed as function of the number of entanglementsZ. In the unentangled regimeη0,linear/η0,ringis virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectationη0,linear/η0,ring=2. In the entanglement regime, theZ-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.
authors.affiliation: FORTH, Institute for Electronic Structure and Laser, Heraklion 71110, Greece.
authors.forename: Rossana
authors.initials: R
authors.lastname: Pasquino
authors.affiliation: University of Athens, Department of Chemistry, Athens 15771, Greece.
authors.forename: Thodoris C
authors.initials: TC
authors.lastname: Vasilakopoulos
authors.affiliation: Pohang University of Science and Technology, Division of Advanced Materials Science and Department of Chemistry, Pohang 790-784, Korea.
authors.forename: Youn Cheol
authors.initials: YC
authors.lastname: Jeong
authors.affiliation: Pohang University of Science and Technology, Division of Advanced Materials Science and Department of Chemistry, Pohang 790-784, Korea.
authors.forename: Hyojoon
authors.initials: H
authors.lastname: Lee
authors.affiliation: FORTH, Institute for Electronic Structure and Laser, Heraklion 71110, Greece.
authors.forename: Simon
authors.initials: S
authors.lastname: Rogers
authors.affiliation: University of Athens, Department of Chemistry, Athens 15771, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Sakellariou
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Allgaier
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takano
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Brás
authors.affiliation: Pohang University of Science and Technology, Division of Advanced Materials Science and Department of Chemistry, Pohang 790-784, Korea.
authors.forename: Taihyun
authors.initials: T
authors.lastname: Chang
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gooßen
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Wim
authors.initials: W
authors.lastname: Pyckhout-Hintzen
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wischnewski
authors.affiliation: University of Athens, Department of Chemistry, Athens 15771, Greece ; King Abdullah University of Science and Technology, Division of Physical Sciences & Engineering, KAUST Catalysis Center, Polymer Synthesis Laboratory, Thuwal, Kingdom of Saudi Arabia.
authors.forename: Nikos
authors.initials: N
authors.lastname: Hadjichristidis
authors.affiliation: Forschungszentrum Jülich GmbH, Jülich 52428, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Richter
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Rubinstein
authors.affiliation: FORTH, Institute for Electronic Structure and Laser, Heraklion 71110, Greece ; University of Crete, Department of Materials Science & Technology, Heraklion 71003, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Vlassopoulos
keywords: entanglements; molecular weight; purification; ring polymers; viscosity