Template Polymerization of Anilines

Template polymerization of aniline onto macromolecular acids is a strategy that has achieved a significant level of success with regards to overcoming PANTs limited solubility. Template polymerization of aniline and aniline... 

Guo ZW, Ruegger H, Kissner R, Ishikawa T, Willeke M, Walde P (2009) Vesicles as soft templates for the enzymatic polymerization of aniline. Langmuir 25(19) 11390-11405... 

The imprinting was accomplished by electrochemical co-polymerization of aniline with 1,2-phenylenediamine, in the presence of DNOC, which led to deposition of the resulting MIP film onto a carbon fibre microelectrode. After removing the DNOC template, the DNOC analyte was selectively determined, with the linear concentration range of 8 x 10 7 to 10 1 M and LOD of 0.2 mM, in the presence of interfering dinitrophenolic pesticides such as binapacryl, and dinobuton. 

Nagarajan R, Samuelson L, Tripathy S, Liu W, Kumar J, Bruno F (2003) Enzymatic polymerization of aniline or phenols around a template. US Patent 6569651... 

An elaboration of this technique, incorporating the concept of template-guided synthesis, is the use of nanoporous matrices such as zeolites and polycarbonates as a template within whole pores to perform the chemical polymerization of aniline monomers. For example, Wu and Bein254 have prepared nanofilaments of conducting PAn in the 3-nm-wide channels (pores) of the aluminosilicate host, MCM-41, through initial adsorption of aniline vapor into the dehydrated host followed by oxidation with (NH)2S208. 

Figure 8.1 Two different pathways for aniline enzymatic polymerization. On top, traditional ortho-coupling. Below, template-assisted enzymatic polymerization of aniline. (Reproduced with permission from [15]. Copyright (1998) American Chemical Society).

Self-doped PANI are very interesting due to their unique electrochemical behavior unlike PANI, the self-doped polymer remains in its doped state in near neutral or alkaline media [28]. Fully self-doped PANIs are not easy to synthesize due to the lower reactivity of acid-functionalized anilines. Kim et al. [29, 30] introduced an alternative approach in the template-assisted enzymatic polymerization of aniline. Previously, only polyanionic templates had been used for PANI synthesis. However, acid-functionalized anilines bear a net anionic charge in aqueous solution, and attempts to use SPS as template with carboxyl-functionalized aniline resulted in red-brown colored polymers with no polaron transitions, regardless of the synthetic conditions. The use of polycationic templates, such as those shown in Figure 8.2 allowed the synthesis of linear and electrically conductive PANIs with self-doping ability due to the doping effect of the carboxyl groups present in the polymer backbone. 

Figure 8.8 Schematic representation of a DNA biosensor based on the DNA-templated enzymatic polymerization of aniline (Reproduced with permission from[71]. Copyright (2007) Wiley-VCH Verlag ).

Chemical Oxidative Polymerization of Aniline Hard (Physical) Template Methods... 

Solid-State Mechanochemical Synthesis Facile template-free solid-state mechano-chemical synthesis of highly branched PANI-NFs with coralloid tree-like superstrueture, via the oxidative polymerization of aniline hydrochloride with FeCl3 6H2O, has been demonstrated [194]. The synthetic yield ( 8%) was comparable to that of the solution interfacial polymerization method. Solid-phase mechanochemical synthesis of branched PANI-NFs was also achieved by using anhydrous FeCl3 as the oxidant [195]. 

Miscellaneous Template-Free Methods Self-assembled PANI-NFs have been prepared by the oxidative polymerization of aniline with APS in an acidic aqueous solution in the presence of HCl [172,204—206], HCl and ethanol [207], HCl and colloidal Au particles... 

Nanoporous Hard-Template Methods PANI-NTs have been prepared by the chemical oxidative polymerization of aniline within the pores of PC nanoporous membranes... 

P.-C. Wang, E. C. Venancio, D. M. Sarno, and A. G. MacDiarmid, Simplifying the reaction system for the preparation of polyaniline nanofibers Re-examination of template-free oxidative chemical polymerization of aniline in conventional low-pH acidic aqueous media. React. Funct. Polym., 69, 217-223 (2009). 

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