Solid State Electrical Conductivity of Radical Polymers as a Function of Pendant Group Oxidation State
Solid State Electrical Conductivity of Radical Polymers as a Function of Pendant Group Oxidation State
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DOI：
10.1021/ma500626t
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发表时间：
2014-06-10
期刊：
影响因子：
5.5
通讯作者：
Boudouris, Bryan W.
中科院分区：
文献类型：
--
作者：
Rostro, Lizbeth;Wong, Si Hui;Boudouris, Bryan W.
我们建立了悬垂基团化学特性与特定自由基聚合物聚（2,2,6,6-四甲基胡椒酰氧基甲基丙烯酸酯）（PTMA）在固体状态下传输电荷的能力之间的关系。自由基聚合物（即具有脂肪族碳骨架和含有稳定自由基基团的悬垂基团的大分子）由于其简单的合成方法、易于调节的电子性质以及相对高性能的电荷传输而在有机电子应用中引起了广泛的关注。由于电荷传输只能通过这些完全无定形的自由基聚合物的悬垂基团发生，因此控制这些官能团的精确化学性质至关重要。具体来说，我们已经确定，通过简单的氧化反应转化垂坠基团功能的脱保护步骤，可以沿着自由基聚合物产生四种不同的化学功能，正如一系列互补光谱技术所监测的那样。在这四种官能团中，只有两种官能团（即稳定的自由基和相应的氧铵离子）能够对大分子的电荷传输能力做出积极的贡献。因此，控制这一脱保护步骤的反应条件，并密切监测所产生的化学功能，对于调整自由基聚合物的电学性质至关重要。然而，如果这些参数控制得很好，我们就能够生成透明的导电薄膜，其原始（即未掺杂）非共轭自由基聚合物的导电性高达（1.5 +/- 0.3）x 10(-5) cm（-1）。
We establish the relationship between pendant group chemical identity and the ability of a specific radical polymer, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), to transport charge in the solid state. Radical polymers (i.e., macromolecules with aliphatic carbon backbones and pendant groups containing stable radical moieties) have attracted much attention in organic electronic applications due to straightforward synthetic methods, easily tunable electronic properties, and relatively high-performance with respect to charge transport. Because charge transport can occur only through the pendant group of these completely amorphous radical polymers, controlling the precise chemical nature of these functional groups is of key import. Specifically, we have determined that the deprotection step, which converts the pendant group functionality through a simple oxidation reaction, can lead to four distinct chemical functionalities along the radical polymer, as monitored by a range of complementary spectroscopic techniques. Of these four functionalities, only two (i.e., the stable free radical and the corresponding oxoammonium cation) are able to contribute positively to the charge transport ability of the macromolecule. As such, manipulating the reaction conditions for this deprotection step, and monitoring closely the resultant chemical functionalities, is critical in tuning the electrical properties of radical polymers. However, if these parameters are controlled well, we are able to generate transparent, conducting thin films of pristine (i.e., not doped) nonconjugated radical polymers with electrical conductivities as high as (1.5 +/- 0.3) x 10(-5) cm(-1).