4460
N. Lou et al. / Polymer 53 (2012) 4455e4460
temperature dependent behavior, as illustrated in 13C NMR exper-
iment, where the mobility of hydrogen-bonded parts is different
from that of the alkyl part connecting them due to the blocky
nature of this molecule.
Program
(2011CB606005),
Shanghai
Pujiang
Program
(10PJ1405400) and Research Fund for the Doctoral Program of
Higher Education (20100073110027). APS acknowledges support
by the U.S. Department of Energy, Office of Basic Energy Sciences,
Division of Materials Sciences and Engineering. Dr. M. M. Guo’s help
with 13C NMR experiment is appreciated.
In another aspect, this unusual decoupling may be related to the
hydrogen-bonding interaction between the molecules. The proba-
bility of forming hydrogen bonds increases with decrease of
temperature, which is likely to increase the probability of connec-
tion between neighbor molecules. The fraction of hydrogen-
bonded molecules increases with decreasing temperature, as
indicated by the characteristic bands at 3220, 3260, and 3420 cmꢁ1
in IR spectra in Fig. 2. Viscous flow requires the rearrangement of
the whole system, which would be affected by the formation of
supramolecules through hydrogen-bonding and their collective
transport, while the dielectric relaxation can proceed local motion
around fluid environment. The temperature variations of the
hydrogen-bonding might have a weaker effect on rotational motion
of molecules than on viscosity, which reflects diffusive displace-
ment of a center of mass. Such a phenomenon could have a general
significance in supramolecular polymer systems.
Appendix A. Supplementary data
Supplementary data related to this article can be found online at
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Acknowledgments
XHM thanks the support by the National Natural Science
Foundation of China (No. 21074070), the National Basic Research