Journal Article

PreJuSER-2462

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Unexpected power-law stress relaxation of entangled ring polymers

Kapnistos, M. ; Lang, M. ; Vlassopoulos, D. ; Pyckhout-Hintzen, W.FZJ* ; Richter, D.FZJ* ; Cho, D. ; Chang, T. ; Rubinstein, M.

2008
Nature Publishing Group Basingstoke

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Please use a persistent id in citations: doi:10.1038/nmat2292

Abstract: After many years of intense research, most aspects of the motion of entangled polymers have been understood. Long linear and branched polymers have a characteristic entanglement plateau and their stress relaxes by chain reptation or branch retraction, respectively. In both mechanisms, the presence of chain ends is essential. But how do entangled polymers without ends relax their stress? Using properly purified high-molar-mass ring polymers, we demonstrate that these materials exhibit self-similar dynamics, yielding a power-law stress relaxation. However, trace amounts of linear chains at a concentration almost two decades below their overlap cause an enhanced mechanical response. An entanglement plateau is recovered at higher concentrations of linear chains. These results constitute an important step towards solving an outstanding problem of polymer science and are useful for manipulating properties of materials ranging from DNA to polycarbonate. They also provide possible directions for tuning the rheology of entangled polymers.

Keyword(s): Molecular Conformation (MeSH) ; Polymers: chemistry (MeSH) ; Viscoelastic Substances: chemistry (MeSH) ; Polymers ; Viscoelastic Substances ; J

Note: We are indebted to J. Roovers for providing the original ring polymers used in this work and for many insightful discussions. We are particularly grateful to S. T. Milner and T. C. B. McLeish for extended discussions that clarified the role of constraint release and significantly improved the quality of the paper. We thank S. Panyukov, S. P. Obukhov, N. Hadjichristidis, B. Loppinet, E. van Ruymbeke, G. Fytas, A.Y. Grosberg, C. Tsenoglou and M. Vamvakaki for helpful discussions. This work was supported by EU (NoE Softcomp NMP3-CT-2004-502235), NSF (CHE-0616925, CBET-0609087), NIH (1-R01-HL0775486A) and KOSEF (CIMS, R0A-2007-000-20125-0).

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Contributing Institute(s):

1. Neutronenstreuung (IFF-5)
2. Streumethoden (IFF-4)
3. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)

Research Program(s):

1. Kondensierte Materie (P54)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Appears in the scientific report 2008

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