Polymerization methods Oxidative coupling

We had discovered a new method for synthesizing high molecular weight polymers which we called polymerization by oxidative coupling. ... 

The formation of poly (2,6-dimethyl-1,4-phenylene oxide) 2, later called PPO resin, represented a new method of polymerization which was termed polymerization by oxidative coupling. PPO was commercialized in 1964 and two year later blends of PPO with polystyrene, NORYL resins that are miscible blends of PPO and polystyrene, were commercially introduced. The scope and mechanism of the oxidative polymerization reaction and the historical development of PPO and its blends have been extensively reviewed previously... 

Polyheterocycles. Heterocychc monomers such as pyrrole and thiophene form hiUy conjugated polymers (4) with the potential for doped conductivity when polymerization occurs in the 2, 5 positions as shown in equation 6. The heterocycle monomers can be polymerized by an oxidative coupling mechanism, which can be initiated by either chemical or electrochemical means. Similar methods have been used to synthesize poly(p-phenylenes). 

Electrochemical synthesis utilizes the ability of a monomer to be self-coupled upon irreversible oxidation (anodic polymerization) or reduction (cathodic polymerization). While this method does not always produce materials with well-defined structures (as do the three other polymerization methods to be discussed), electropolymerization, nonetheless, is a rather convenient alternative, avoiding the need for polymer isolation and purification. Of these two routes, anodic polymerization is the most widely explored as monomers such as pyrrole and thiophene are relatively electron-rich and prone to oxidation. For this reason the anodic route will be the focus of the remainder of this presentation. 

Touring the last decade, catalyzed oxidative coupling has gained wide-spread interest as a novel and general polymerization method. Various polymer systems of scientific and commercial interest have been prepared by this novel technique. Such polymer systems include polyphenylene oxides) (9, 13, 25), of which poly(2,6-dimethylphenylene oxide) (PPO) is produced commercially polyphenylenes (21) poly-... 

The telechelica,(i -bis(2,6-dimethylphenol)-poly(2,6-dimethylphenyl-ene oxide) (PP0-20H) [174-182] is of interest as a precursor in the synthesis of block copolymers [175] and thermally reactive oligomers [179]. The synthesis has been accomplished by five methods. The first synthetic method was the reaction of a low molecular weight PPO with one phenol chain end with 3,3, 5,5 -tetramethyl-l,4-diphenoquinone. This reaction occurred by a radical mechanism [174]. The second method was the electrophilic condensation of the phenyl chain ends of two PPO-OH molecules with formaldehyde [177,178], The third method consists of the oxidative copolymerization of 2,6-dimethylphenol with 2,2 -di(4-hydroxy-3,5-di-methylphenyl)propane [176-178]. This reaction proceeds by a radical mechanism. A fourth method was the phase transfer-catalyzed polymerization of 4-bromo-2,6-dimethylphenol in the presence of 2,2-di(4-hy-droxy-3,5-dimethylphenyl)propane [181]. This reaction proceeded by a radical-anion mechanism. The fifth method developed was the oxidative coupling polymerization of 2,6-dimethylphenol (DMP) in the presence of tetramethyl bisphenol-A (TMBPA) [Eq. (57)] [182],... 

Electrochemical oxidation of resonance stabilized aromatic molecules is a common and singular method used to prepare CPs. It involves the oxidative coupling of monomers and is an ideal method to prepare conductive films that show reversible redox reaction. The polymerization can be monitored by in situ combination of the electrolysis system and appropriate spectroscopic or electro-analytical techniques the electrochemistry of CPs is the subject of a recent review with 748 references. 

Three methods for the construction of chiral polynaphthalenes have been described. In the first case, 2,2 -dihydroxy-6,6 -binaphthalenes were subjected to the optimized asymmetric oxidative coupling conditions, yielding the corresponding chiral polymers (a). It was found that each biaryl coupling step during the polymerization process is independent of existing axial chirality... 

When one considers how synthetic chemistry has impacted the development of conjugated polymers, there is no better example than the poly(3-alkylthio-phenes) (P3ATs, 4). Early work focused on oxidative polymerization methods as a means of preparing soluble forms of this polymer. Subsequently, Grignard coupling reactions were able to prepare the polymer directly in the... 

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