An enzymatically synthesized polyaniline: A solid-state NMR study
An enzymatically synthesized polyaniline: A solid-state NMR study
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DOI：
10.1021/ma035252
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发表时间：
2004-06-01
期刊：
影响因子：
5.5
通讯作者：
Cholli, AL
中科院分区：
文献类型：
--
作者：
Sahoo, SK;Nagarajan, R;Cholli, AL
用固体C-13和N-15 CP/MAS核磁共振波谱分析了聚苯胺氧化酶促聚合制备的掺杂(合成)导电、脱掺碱和还原导电聚苯胺(PANI)的分子结构和电子结构的变化。利用天然生物催化剂如辣根过氧化物酶(HRP)和人工合成的仿生催化剂，特别是聚乙二醇偶联的血红素(PEG-hematin)，在pH为4.3时酶促合成了聚苯胺。以聚(乙烯基膦酸)(PVP)、聚对苯磺酸(SPS)和十二烷基苯磺酸(DBSA)为模板，进行了HRP催化的PANI酶促聚合反应。C-13和N-15 CP/MAS核磁共振波谱特征表明，聚乙二醇酶促聚合得到的PANI与化学合成的掺杂(合成)导电形式的类似物最相似。系统地研究了不同pH条件下的还原过程，揭示了从脱掺杂基态向掺杂导电态转变过程中的结构变化。固体核磁共振数据还表明，在较高的掺杂水平下，极化子的贡献有所减少。来自IN CP/MAS核磁共振数据的端基分析提供了有关酶聚合PANI样品的分子量的信息。
The variation in molecular and electronic structure of doped (as synthesized) conducting, dedoped base, and redoped conducting forms of polyaniline (PANI) prepared by oxidative enzymatic polymerization of aniline with and without the presence of polyelectrolyte template was analyzed by solid-state C-13 and N-15 CP/MAS NMR spectroscopy. Polyanilines were enzymatically synthesized using a natural biocatalyst such as horseradish peroxidase (HRP) at pH 4.3 and a synthetic biomimetic catalyst, specifically poly(ethylene glycol)-coupled hematin (PEG-hematin), at pH 1.0. The HRP-catalyzed enzymatic polymerization of PANI was carried out in the presence of macromolecular polyelectrolyte templates such as poly(vinylphosphonic acid) (PVP), poly(4-styerenesulfonate) (SPS), and dodecylbenzenesulfonic acid (DBSA). C-13 and N-15 CP/MAS NMR spectral features indicate that the PANI obtained by PEG-hematin-catalyzed enzymatic polymerization resembles most with chemically synthesized analogues in its doped (as synthesized) conducting form than other forms of PANI. A systematic experiment involving a redoping process at different pH levels shows the structural changes during the transformation from dedoped base form to redoped conducting form. Solid-state NMR data also indicate a decrease of polaronic contribution at the higher doping level. End-group analysis from IN CP/MAS NMR data provides information on the molecular weight of the enzymatically polymerized PANI sample.