Polymerization 3-methylthiophene

Cyclic voltammetric studies involving polymers, 558 and the nature of charge carriers, 561 and the nucleation loop, 557 of poly (3-methylthiophene), 564 and parallel-band electrodes, 570 Cyclic voltammograms as a function of scan rate, 559 involving polymerization, 559 with polyanaline, 566 of polypyrrole film, 581... 

Figure 30. In situ measurements of the time evolution of the Cu K-edge when a platinum electrode coated with a polymeric film of poly (methylthiophene) is cathodically polarized in an aqueous solution containing 50 mM CuCl2. (From Ref. 105, with permission.)... 

Closer reading of the published work, reveals that the polymers are not wholly soluble and that the extent of solubility is dependent on the solvent265). In the case of a butylthiophene-methylthiophene copolymer, hot THF solubilizes a fraction of low molecular weight which forms brittle films, while hot xylene extracts a higher molecular weight polymer which forms tough films. There remains an insoluble, and presumably cross-linked residue. The microstructure of the polymer is presumably quite dependent on the polymerization method and conditions. 

The template-assisted synthetic strategies outlined above produce micro- or mesoporous stmetures in which amorphous or crystalline polymers can form around the organic template ligands (174). Another approach is the use of restricted spaces (eg, pores of membranes, cavities in zeolites, etc.) which direct the formation of functional nanomaterials within thek cavities, resulting in the production of ultrasmaU particles (or dots) and one-dimensional stmetures (or wkes) (178). For example, in the case of polypyrrole and poly(3-methylthiophene), a solution of monomer is separated from a ferric salt polymerization agent by a Nucleopore membrane (linear cylindrical pores with diameter as small as 30 nm) (179—181). Nascent polymer chains adsorb on the pore walls, yielding a thin polymer film which thickens with time to eventually yield a completely filled pore. De-encapsulation by dissolving the membrane in yields wkes wherein the polymer chains in the narrowest fibrils are preferentially oriented parallel to the cjlinder axes of the fibrils. 

The electrosynthesis of polythiophene (PT) from thiophene must be performed under extremely anhydrous conditions, quite in contrast to polypyrrole [334]. Polymerization of 3-methylthiophene and bithiophene is much less sensitive to water. The advantage of PT is a higher theoretical capacity and a very positive potential (cf. Table 7). It is for these reasons that its application as a positive electrode in rechargeable lithium batteries [335-338] and in a metal-free PPy/PT cell [339] has been considered. Derivatives such as dithienothiophene [340] or rra/is-l,2-di(2-thienyl)ethylene [341] have also been polymerized, but the polymer materials suffer from low theoretical capacities [337]. 

Hydrogen evolution Irom the electroreduction of protons at different modified polymer electrodes was first investigated by Tourillon and Gamier, who studied the inclusion of bimetallic Ag-Pt particles into poly-3-methylthiophene(PMeT) and observed their electrocatalytic properties towards the proton reduction reaction [46], They demonstrated the positive effect of the Ag particles (from 15 /ig/cm ) on the reduction current due to an increase of the electrode conduction at low potentials, where PMeT is in its neutral undoped state, and put in evidence a minimum Pt loading (of about 10 tg/cm for a 170 nm thick film) for obtaining an enhanced catalytic activity compared to a platinized Ag-coated Au electrode without a polymeric film. A remarkable stability with time was observed under polarization at a constant potential ( — 0.4 V/SCE) without degradation of the modified electrode. 

There is already a large number of different conductive polymers. A typical monomer is 3-methylthiophene, which can be electrically polymerized to a polymer coupled by the 2-and 5-positions of the monomer. In the oxidized form, usually called doped , the chains contain positive charges at about every fourth monomer unit. In order to keep the polymer layer electrically neutral, also counter anions should be present in the polymer matrix. It is analytically interesting that the diffusion rate of these counter anions controls the rate of oxidation and reduction of the polymer, and the diffusion rate depends on the size, degree of solvation etc. of the anion. Hence, by a suitable choice of the polymer, it should be possible, at least in principle, to tailor-make sensors for different anions. In addition, it has been shownthat electrically neutral polymers can be incorporated from the solution into the polymer matrix during the polymerization process. This of course extends enormously the possibilities for developing selective sensors without undue efforts to synthesize new electrically polymerizable monomers. 

We have used our potentiostat system in a study of these basic phenomena with poly-3-methylthiophene (p3MeT) as a model polymer. The film was galvanostatically polymerized onto a Pt-electrode in a 0.1 M acetonitrile solution of 3MeT and (n-Bu)4NC104 using a current density of 2 mA/cm. The total charge was 100 mC/cm which corresponds to an approximate film thickness of 100 nm. Some chronoamperometrical results with different anions are shown in Fig.5. As can be seen the time scale of the reduction process is relatively... 

Arbizzani, C., F. Soavi, and M. Mastragostino. 2006. A novel galvanostatic polymerization for high specific capacitance poly(3-methylthiophene) in ionic liquid. Journal of Power Sources 162 735-737. 

We recently succeded in forming intrazeolite polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh) and poly(3-methylthiophene) (P3MTh)l by oxidative polymerization inside the cavities of different zeolites, as demonstrated by vibrational, ESR, and electronic absorption data. It was observed that the dimensionality and pore size of the host determine the polymerization rates and intrazeolite products. This communication compares the above zeolite/polymer systems and discusses evidence for polymerization inside the host channel structures. 

We have demonstrated that oxidative polymerization reactions leading to conducting polymers can be carried out within the channel systems of zeolites. Acidic zeolite forms are required to synthesize intrazeolite polyaniline by analogy to the oxidative coupling of aniline in acidic solutions. The presence of intrazeolite oxidants such as Cu(II) and Fe(III) ions is fundamental for the polymerization of pyrrole, thiophene and 3-methylthiophene. The degree of polymer chain oxidation and probably the chain lengths are influenced by the dimension ity of the zeolite channels. 

Utilizing an electrocopolymerization technique, various conducting copolymer layered structures were constructed. The copol)mier composition, and the thickness of the polymerized copolymer, are controlled easily in the electrolytic polymerization process (Fig. 7). Fig. 8 is an example of such depth profile-controlled multilayers, consisting of polypyrrole and copoly(pyrrole/3-methylthiophene). The present method will allow nm-level thickness control. 

MWCNTs/poly(3- methylthiophene) (MWCNT-PMTH) In-situ chemical polymerization Pellets Methane, acetone, acetaldehyde, benz-aldehyde, tetrahydro-furan, methanol, and ethanol [36]... 

Electrochemical polymerization of 3-methylthiophene (Fig. 3.22] follows an RC formation and the growth of 3-mTh is accomplished by electrophilic attack of an RC at the end of the growing chain on the neutral monomer unit, which is followed by oxidation and deprotonation steps. The process is suggested as neither a classical step growth nor a classical chain polymerization but something in between. ... 

The responses of gophers to the weasel mixture and single anal gland compounds are illustrated in Figure 3. There was no difference in responses between males and females in these trials. Gophers clearly avoided the 2-propylthietane, polymerized 3-propyl-l,2-dithiolane, and the weasel mixture. They also tended to avoid the 3,3-dimethyl-l,2-dithiolane from the ferret with the following results from 3 trials (control vs. treatment) 14-9 14-9 8-1. The control test, fresh 3-propyl-l,2-dithiolane, and 2-methylthiophene (novel odor) had little effect on gopher behavior. 

A copolymer of pyrrole and thiophene nano-fibrUs was electrochemically polymerized within the pores of microporous, anodic, aluminum oxide template membranes [105]. The copolymer nucleated and grew on the pore wall of the membrane since the polymers were cationic and the membrane had anionic sites on the pore wall. The length, thickness, and diameter of the copolymer nanofibrils could be controlled and with higher applied potential, more thiophene units were incorporated into the copolymer nanofibrUs [105]. Copolymer nanofibrils of pyrrole and aniline were also electrochemically polymerized within the pores of microporous, anodic, aluminum oxide template membranes [106]. Copolymer nanofibrils of PPy and poly(3-methylthiophene) prepared chemically in the microporous aluminum oxide template showed higher conductivity than the homopolymers did [107]. 

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