3-methylthiophene monomers

Pyrrole, thiophene and 3-methylthiophene monomers were loaded into the degassed zeolites from either the vapor phase in small quartz reactors, or from zeolite suspensions in water and hexane (Table 1). Bulk polymers were synthesized according to published procedures. I l l ... 

A number of approaches are available to improve the morphology and homogeneity of electrochemically deposited conducting polymer films. Priming of the electrode surface with a monolayer of adsorbed or covalently bonded monomer leads to more compact deposits of polyaniline,87,88 poly thiophene,80 and polypyrrole.89,90 Electrode rotation has been shown to inhibit the deposition of powdery overlayers during poly(3-methylthiophene) deposition.81... 

Polypyrrole was the first conducting polymer used as ion-to-electron transducer in solid-state ISEs [43], and is still one of the most frequently used [45-68]. Other conducting polymers that have been applied as ion-to-electron transducers in solid-state ISEs include poly(l-hexyl-3,4-dimethylpyrrole) [69,70], poly(3-octylthiophene) [44,70-74], poly(3,4-ethylenedioxythiophene) [75-86], poly(3-methylthiophene) [87], polyaniline [44,67,73,88-99], polyindole [100,101], poly(a-naphthylamine) [102], poly(o-anisidine) [67] and poly(o-aminophenol) [103], The monomer structures are shown in Fig. 4.1. 

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. 

An alternative, less sophisticated approach to regioregular substituted polythiophenes is the use of asymmetric 3,4-disubstituted thiophene monomers as substrates, resulting in the selective activation of either the 2- or 5- positions on the thiophene ring. Using this method, poly(3-alkoxy-4-methylthiophenes) with > 95% HT couplings have been prepared via FeCl3 oxidation.48 59... 

The grafting of poly-3 methylthiophene (PMeT) on the Pt wire involves the oxidation of the monomer, 3-methylthiophene, 0.5 M in CH3CN + 0.5 M N(C4H9)4S03CF3 at 1.35 V/SCE (satured calomel electrode). The polymer is formed directly in its doped conducting state. This modified electrode is put in a 3 mm-thick electrochemical cell composed of a Teflon ring covered by two Kapton windows. An aqueous copper... 

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. 

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 electrocatalytic behavior of ECPs toward the electropolymerization of other monomers has also been mentioned and recently investigated by Zotti et al. [59] it has been demonstrated that electropolymerization of 3-methylthiophene could be catalyzed by previously electrodeposited polyterthio-phene because of the formation of a charge transfer complex during the electropolymerization process (see also Section 18.2). 

The monomer, sodium 2-(4-methyl-3 -thienyloxy)ethanesulfonate was synthesized in three steps from 3-bromo-4-methylthiophene (Figure... 

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