Dynamics of polymer molecules using neutron spin—echo
Dynamics of polymer molecules using neutron spin—echo
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使用中子自旋回波研究聚合物分子动力学
DOI：
10.1002/pi.4980190203
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
J. Higgins
中科院分区：
文献类型：
--
作者：
J. Higgins
用中子自旋回波技术研究了单链聚合物在稀溶液和熔体中的动力学。在稀溶液中，分子内的运动被描述为包含流体动力相互作用的Rouse链的一级近似运动(ZIM)。它的特征是逆关联时间，该时间可由温度、溶剂粘度和链段大小归一化，并且对于长链，在小散射角时变化为Q3(Q是散射时波矢的变化)。在很低的Q矢量下，可以观察到预测的“普遍”状态，但在大多数可达范围内，化学结构也变得重要。对于短链，偏离Q3行为与整体分子扩散有关。在熔体中，链式纠缠起作用，改变了简单的Rouse运动。关联函数由熔体动力学的旋转模型预测的短距离和时间的Rouse运动和长时间的慢运动相结合来描述。
The dynamics of single polymer chains have been investigated in dilute solution and in the melt using the neutron spin—echo technique. In dilute solution the intramolecular motion is described to a first approximation by that for a Rouse chain incorporating hydrodynamic interactions (Zimm). It is characterised by an inverse correlation time which may be normalised by temperature, solvent viscosity and segment size, and which for long chains varies as Q3 at small scattering angles (Q is the change in wavevector on scattering). At very low Q vectors the predicted ‘universal’ regime is observed, but over most of the accessible range chemical structure also becomes important. For short chains, deviations from this Q3 behaviour are associated with overall molecular diffusion. In the melt, chain entanglements come into play and modify the simple Rouse-type motion. The correlation functions are described by a combination of Rouse motion over short distances and times and a long-time slow-motion predicted by the reptation model of melt dynamics.