Vasilakopoulos, Thodoris C.
Rogers, Simon A.
Allgaier, Jürgen B.
Brás, Ana Rita E
Richter, Dieter R.
Rubinstein, Michael H.
KAUST DepartmentKAUST Catalysis Center (KCC)
Physical Sciences and Engineering (PSE) Division
Chemical Science Program
Polymer Synthesis Laboratory
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AbstractWe 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 a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,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 ring 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 ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±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. © 2013 American Chemical Society.
SponsorsWe are grateful to Frank Snijkers, Hiroshi Watanabe, Jorg Baschnagel, and Vlasis Mavrantzas for helpful discussions. We acknowledge partial support from EU (ITN DYNACOP, grant 214627; FP7 Infrastructure ESMI, GA 262348). T.C. acknowledges the support from NRF (2008-0061892 and 2012R1A2A2A01015148). MR acknowledges support from the NSF, grants CHE-0911588, DMR-0907515, DMR-1121107, and DMR-1122483, the NIH, 1-P5-HL107168, 1-P01-HL108808-01A1, and the Cystic Fibrosis Foundation.
PublisherAmerican Chemical Society (ACS)
JournalACS Macro Letters