Authors Kapnistos, M. ; Lang, M. ; Vlassopoulos, D. ; Pyckhout-Hintzen, W. ; Richter, D. ; Cho, D. ; Chang, T. ; Roovers, J. ; Rubinstein, M.
Title Unexpected power-law stress relaxation of entangled ring polymers
Date 05.12.2008
Number 15903
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.
Publisher Nature Materials
Wikidata Q33379595
Citation Nature Materials 7 (2008) 997-1002
Tags viscoelastic properties cyclic polystyrene fixed obstacles tube dilation dynamics reptation molecules melt diffusion viscosity

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