Molecular dynamics of hyperbranched polyesters in the confinement of thin films
Molecular dynamics of hyperbranched polyesters in the confinement of thin films
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薄膜约束中超支化聚酯的分子动力学
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
F. Kremer
中科院分区：
文献类型：
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作者：
A. Serghei;Y. Mikhailova;H. Huth;C. Schick;K. Eichhorn;B. Voit;F. Kremer
摘要：采用宽带介电谱研究超支化聚酯（AB 1B 2型，以-OH和-OCOCH 3为末端基团）薄膜的分子动力学。检测到三个弛豫过程：α，β和γ。虽然后两者不受限制的影响，一个显着的效果是观察到的α弛豫：随着膜厚度的降低，缓慢的动态玻璃化转变的弛豫模式逐渐抑制，导致平均弛豫速率的增加和线性降低的介电强度。这归因于位于超支化大分子结构外围的聚合物链段的限制固定化。
Abstract.Broadband Dielectric Spectroscopy is employed to investigate the molecular dynamics in thin films of hyperbranched polyesters (type AB1B2, with -OH and -OCOCH3 as terminal groups). Three relaxation processes are detected: alpha, beta and gamma. While the latter two are not influenced by the confinement, a pronounced effect is observed on the alpha relaxation: with decreasing film thickness the slower relaxation modes of the dynamic glass transition are gradually suppressed, resulting in an increase of the average relaxation rate and in a linear decrease of the dielectric strength. This is attributed to an immobilization in confinement of the polymeric segments located at the periphery of the hyperbranched macromolecular structures.