Thermal fluctuations in polymer gels investigated by neutron spin echo and dynamic light scattering
Thermal fluctuations in polymer gels investigated by neutron spin echo and dynamic light scattering
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DOI：
10.1021/ma020507p
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发表时间：
2002-10-22
期刊：
影响因子：
5.5
通讯作者：
Geissler, E
中科院分区：
文献类型：
--
作者：
Hecht, AM;Horkay, F;Geissler, E
测量所描述的中子自旋回波和准弹性光散射在端连接的聚氟硅氧烷（PFS）凝胶在丙酮中溶胀，以及在同等的解决方案。在同一系统上进行了小角弹性中子散射测量。对于PFS-丙酮系统，动态光散射和中子自旋回波产生类似的结果的特征弛豫速率和浓度波动散射的强度。它示出的自旋回波衰减的松弛部分所描述的相同的热力学浓度波动，定义系统的渗透模量。集体扩散系数和动态散射光的强度被发现是在凝胶中比在溶液中更大。这种差异表明交联网络中的聚合物溶剂摩擦系数低于未交联溶液中的摩擦系数。
Measurements are described involving neutron spin echo and quasi-elastic light scattering in an end-linked polyfluorosilicone (PFS) gel swollen in acetone as well as in the equivalent solution. Small-angle elastic neutron scattering measurements were performed on the same system. For the PFS-acetone system, both dynamic light scattering and neutron spin echo yield similar results for the characteristic relaxation rates and for the intensity scattered by concentration fluctuations. It is shown that the relaxing part of the spin echo decay is described by the same thermodynamic concentration fluctuations that define the osmotic modulus of the system. Both the collective diffusion coefficient and the intensity of the dynamically scattered light are found to be greater in the gel than in the solution. This difference indicates that the polymer solvent friction coefficient in the cross-linked network is lower than in the un-cross-linked solution.