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Journal of Chemical Physics / Volume 105 / Issue 21

J. Chem. Phys. 105, 9657 (1996); http://dx.doi.org/10.1063/1.472774 (9 pages)

Order fluctuations in the mesophase of polydiethylsiloxane as studied by the dipolar‐correlation effect on the stimulated echo

F. Grinberg1, R. Kimmich1, M. Möller2, and A. Molenberg2

1Universität Ulm, Sektion Kernresonanzspektroskopie, 89069 Ulm, Germany
2Universität Ulm, Abteilung, Makromolekulare Chemie, 89069 Ulm, Germany

(Received 23 July 1996; accepted 22 August 1996)

Order fluctuations in polydiethylsiloxane (PDES) mesophase are studied using the dipolar‐correlation effect on the stimulated echo. The attenuation of the stimulated echo is described on the basis of a two‐site slow exchange model. The conclusion is that collective chain fluctuations result in temporarily and locally ordered and temporarily and locally defect‐enriched states. The local order parameter is inhomogeneously distributed in the samples as indicated by the absence of any oscillatory modulation of the dipolar‐correlation effect. The mean exchange time between the two mobility states varies in the temperature range of the mesophase between 0.1 and 1 s. It turned out to be an exponential function of the reduced temperature relative to the isotropization temperature. Apart from this implicit function no explicit dependence on the molecular weight could be detected. This suggests that the exchange phenomenon and the type of the order fluctuations are features universal for the PDES mesophase. © 1996 American Institute of Physics.

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KEYWORDS and PACS

Keywords

SILOXANES, MESOPHASES, FLUCTUATIONS, ORDER PARAMETERS, ELECTRIC DIPOLES, DIPOLE MOMENTS, CORRELATION TIME, POLYMERIZATION, RELAXATION TIME

PACS

  • 82.35.-x

    Polymers: properties; reactions; polymerization

  • 36.20.Hb

    Configuration (bonds, dimensions)

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.472774

PUBLICATION DATA

ISSN

0021-9606 (print)  
1089-7690 (online)

For access to fully linked references, you need to log in.
    F. Grinberg and R. Kimmich, J. Chem. Phys. 103, 365 (1995JCPSA6000103000001000365000001).

    F. Grinberg and R. Kimmich, J. Chem. Phys. 105, 3301 (1996JCPSA6000105000008003301000001).

    P. W. Anderson and P. R. Weiss, Rev. Mod. Phys. 25, 269 (1953).


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