Charge Transport and Dipolar Relaxations in Hyperbranched Polyamide Amines
Charge Transport and Dipolar Relaxations in Hyperbranched Polyamide Amines
复制标题
超支化聚酰胺胺中的电荷传输和偶极弛豫
DOI：
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发表时间：
2009
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：
J. Sangoro;G. Turky;M. Rehim;C. Iacob;S. Naumov;A. Ghoneim;J. Kärger;F. Kremer
结合宽带介电光谱、脉冲场梯度核磁共振（PFG NMR）和差示扫描量热法研究了新型超支化聚酰胺胺中的电荷输运和偶极弛豫。在较高温度下，介电光谱主要由电导率贡献主导（掩盖了结构α-弛豫过程），而在较低温度下，两个样品观察到两个次级偶极弛豫过程。基于Einstein和Einstein−Smoluchowski关系，从介电光谱中提取了扩散系数，与独立的PFG核磁共振测量结果定量一致。它表现出Vogel - Fulcher - Tammann温度依赖性，而载流子的有效数密度随温度的变化很小。研究发现，超支化聚合物的电荷输运和结构α-弛豫的去耦指数为~ 7。
Broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance (PFG NMR), and differential scanning calorimetry are combined to study charge transport and dipolar relaxations in novel hyperbranched polyamide amines. The dielectric spectra are dominated by conductivity contributions at higher temperatures (masking out the structural α-relaxation process), whereas two secondary dipolar relaxation processes are observed at lower temperatures for the two samples investigated. Based on Einstein and Einstein−Smoluchowski relations, the diffusion coefficient is extracted from the dielectric spectra—in quantitative agreement with independent PFG NMR measurements. It exhibits a Vogel−Fulcher−Tammann temperature dependence, while the effective number density of the charge carriers varies only weakly with temperature. Charge transport and structural α-relaxation are found to be characterized by a decoupling index of ∼7 for the hyperbranched polymers studied.