Polypyrrole self assembly

FIG. 8 Si02 AFM image of six bilayers in situ self-assembled layer-by-layer films of polypyrrole coated with Si02 and poly(styrene sulfonate). 

The polypyrrole molecular interface has been electrochemically synthesized between the self-assembled protein molecules and the electrode surface for facilitating the enzyme with electron transfer to the electrode. Figure 9 illustrates the schematic procedure of the electrochemical preparation of the polypyrrole molecular interface. The electrode-bound protein monolayer is transferred in an electrolyte solution containing pyrrole. The electrode potential is controlled at a potential with a potentiostat to initiate the oxidative polymerization of pyrrole. The electrochemical polymerization should be interrupted before the protein monolayer is fully covered by the polypyrrole layer. A postulated electron transfer through the polypyrrole molecular interface is schematically presented in Fig. 10. 

Kapui et al. prepared a novel type of polypyrrole films [168]. The film was impregnated by spherical styrene-methacrylic acid block copolymer micelles with a hydrophobic core of 18 nm and a hydrophilic corona of 100 nm. The properties of the micelle-doped polypyrrole films were investigated by cyclic voltammetry and SECM. It was found that the self-assembled block copolymer micelles in polypyrrole behave as polyanions and the charge compensation by cations has been identified during electrochemical switching of the polymer films. 

A few groups examined larger systems by in situ STM. Examples include the deposition of polymers, polypyrrole, polyaniline,and polymethylthiophene. Hagenstrom et al. reported studies on imaging of self-assembled monolayers (SAM). "" They showed the possibihty of imaging detailed stmetures, and order-disorder transitions in dependence on electrochemical parameters. 

Figure 9.17 AFM images of PPy-DNA nanowires and nanopores on a SiOJSi surface (a) nanowires observed 3 h after preparation (b) and (c) two representative images of nanorope samples observed after standing for 24 h. (Reprinted with permission from Advanced Functional Materials, Self-Assembly of DNA-Templated Polypyrrole Nanowires Spontaneous Formation of Conductive Nanoropes by S. Pruneanu, S. A. Farha Al-Said, L. Dongetal., 18, 16, 2444-2454. Copyright (2008) Wiley-VCH)...

S. Pruneanu, S.A.F Al-Said, L. Dong, T.A. Hollis, M.A. Galindo, N.G. Wright, A. Houton, and B.R. Horrocks, Self-assembly of DNA-templated polypyrrole nanowires spontaneous formation of conductive nanoropes, Adv. Func. Mater., 18, 2444-2454 (2008). 

Figure 15.7 SEM images (A) regular PPy and (B) templated PPy. (Reprinted with permission from Synthetic Metals, Templated polypyrrole electro-polymerization Self-assembled bundles of bilayer membranes of amphiphiles and their actuation behavior by K. Kagawa, P. Qian, A. Tanaka and T. M. Swager, 157, 18-20, 733-738. Copyright (2007) Elsevier Ltd)...

Sayre, C.N., and D.M. Collard. 1997. Electrooxidative deposition of polypyrrole and polyaniline on self-assembled monolayer modified electrodes. Langmuir 13 714. 

Gorman, C.B., H.A. Biebuyck, and G.M. Whitesides. 1995. Fabrication of patterned, electrically conducting polypyrrole using a self-assembled monolayer A route to all-organic circuits. Chem Mater 7 526. 

Zhou, E, et al. 2004. Manipulation of the ultimate pattern of polypyrrole film on self-assembled monolayer patterned substrate by negative or positive electrodeposition. Surf Sci 561 1. 

Innovative microstructures have been produced by self-assembly during electropolymerization in the presence of surfactants. Dai and coworkers have recently shown that bowl-shaped microcontainers of polypyrrole can be produced by stabilizing H2 gas bubbles on the electrode surface [79]. Carboxylic acid dopants have also been used, resulting in hollow nanotubes of polyaniline [80]. 

Collard et al. [57] reported the self-assembly of monomers, potassium 3-(3-alkylpyrrol-l-yl)propanesulfonates (Figure 5.14), and their subsequent electrochemical synthesis on gold electrodes to form lamellar structures of substituted polypyrrole. The fact that 3-(3-alkylpyrrol-l-yl)propanesulfonates possess amphiphilic character by virtue of the hydrophobic alkyl chain and hydrophilic ionic sulfonate head group, was used to form micellar solutions above critical concentrations. A... 

Poly (thiophene)s are of particular interest as electfochromic materials owing to their chemical stability, ease of synthesis and processability. For the most part, current research has been focused on composites, blends and copolymer formations of several conjugated polyheterocyclics, polythiophene and its derivatives, especially PEIX)T. In one example, poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS) composite films were prepared by Sonmez et al. for alternative electrochromic applications [50]. Thin composite films comprised of PEDOT/PAMPS were reported to switch rapidly between oxidized and neufial states, in less than 0.4 s, with an initial optical contrast of 76% at A.max. 615 nm. Nanostructured blends of electrochromic polymers such as polypyrrole and poly(3,4-ethylenedioxythiophene) were developed via self-assembly by Inganas etal. for application as an electrochromic window [26]. Uniir etal. developed a graft-type electrochromic copolymer of polythiophene and polytetrahydrofuran for use in elecfiochromic devices [51]. Two EDOT-based copolymers, poly[(3,4-ethylenedioxythiophene)-aZ/-(2,5-dioctyloxyphenylene)] and poly[(3,4-ethylenedioxythiophene)-aft-(9,9 -dioctylfluorene)] were developed by Aubert et al. as other candidates for electrochromic device development [52],... 

Ti02 particles ( 20 nm diameter prepared from TiCl3, pH 2.5) can be obtained at the surface of a photochemical electrode to construct sohd light-sensitive solar cells. " Simultaneously, polypyrrole, which is formed on electrochemical polymerization of pyrrole adsorbed in the electrode s pores, precipitates on these particles. " These structurally controlled templates are analogues of self-assembling supramolecu-lar ensembles. The procedure for the preparation of supramolecular systems for... 

---