VARIABLE-TEMPERATURE EPR AND TRANSPORT STUDIES ON POLY(4,4'-METHYLENEDIANILINE) - EVIDENCE FOR BIPOLARONS

被引：14

作者：

ANAND, J ^{[1
]}

PALANIAPPAN, S ^{[1
]}

SATHYANARAYANA, DN ^{[1
]}

机构：

[1] INDIAN INST SCI, DEPT INORGAN & PHYS CHEM, BANGALORE 560012, KARNATAKA, INDIA

来源：

JOURNAL OF PHYSICAL CHEMISTRY | 1995年 / 99卷 / 25期

关键词：

D O I：

10.1021/j100025a039

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The correlation between magnetic and transport properties is examined by studying poly(4,4'-methylenedianiline) (PMDA) salts and their bases using EPR and conductivity measurements. Five different PMDA salts (doped polymers) were prepared by chemical polymerization of 4,4'-methylenedianiline using different protonic acids. The PMDA bases were obtained by dedoping the salts using ammonium hydroxide. Ambient temperature electrical conductivity measurements show evidence for the doped PMDA system to be highly disordered. The EPR spectra of the samples were recorded in the range 20-200 degrees C, and the results were analyzed on the basis of-the polaron-bipolaron model, which is typical of nondegenerate systems. Both PMDA salts and their bases consist of self-trapped, highly mobile polarons or radical cations. EPR studies on PMDA salts show evidence for the presence of thermally activated and temperature-independent (or Pauli type) paramagnetism while the bases show thermally activated, Pauli and Curie-Weiss types of paramagnetism. The paramagnetism arises due to polarons. It is proposed that charge transport takes place through both polarons and bipolarons.

引用

页码：10324 / 10328

页数：5

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