Alternating copolymers heterocyclic

Copolymerisations of heterocyclic and heterounsaturated monomers generally lead to random copolymers with a prevailing content of the heterocyclic monomer and to alternating or nearly alternating copolymers, depending on the kind... 

Zwitterions are the propagating species in a number of spontaneous polymerizations that occur upon mixing electron donor and acceptor monomers. Several reviews of spontaneous polymerizations via zwitterion intermediates are available [317-323]. In this novel type of polymerization reaction there is no need to add an initiator or catalyst. Alternating copolymers have been obtained in some cases when at least one of the monomers contains a heterocycle. In these polymerizations a nucleophilic monomer (Mn) and an electrophilic monomer (Me) react to form a zwitterion [Eq. (89)]. This zwitterion is referred to as a genetic zwitterion. ... 

Cationic complexes of Pd11, Ni11, and Ru11 in syntheses of alternating copolymers of CO with heterocyclic vinylic monomers 02IZV1475. 

Polypyrrole copolymers with perfectly alternating units of pyrrole with another single heterocycle are not known. Alternating copolymers of pyrrole with bithiophene are prepared by electrochemical polymerization of the three-membered oligomer, 2,5-di-2-(thienyl)-pyrrole [11,12]. Even the homopolymerization of 2-thienylpyrrole does not really lead to alternating units of pyrrole and thiophene because this monomer must dimerize after oxidation. What results is a copolymer of bipyrrole and bithiophene because of the different values for the oxidation potentials of pyrrole, thiophene, bithiophene, etc. 

Thiophene-Complex Arylenes. An alternating copolymer of bis-thienyl and corenene has been reported [822]. Numerous other electroactive copolymers containing more complex heterocyclic rings have been prepared [823-829] (Fig. 57). 

Since oxiranes are representative heterocyclic monomers containing an endo-cyclic heteroatom, and the most commonly polymerised of such monomers, they have been subjected to copolymerisations with heterocyclic monomers containing both an endocyclic and an exocyclic heteroatom. Coordination copolymerisations of heterocyclic monomers with different functions are focused on oxirane copolymerisation with cyclic dicarboxylic acid anhydride and cyclic carbonate. However, the statistical copolymerisation of heterocyclic monomers with an endocyclic heteroatom and monomers with both endocyclic and exocyclic heteroatoms have only a limited importance. Also, the block copolymerisation of oxirane with lactone or cyclic dicarboxylic acid anhydride is of interest both from the synthetic and from the mechanistic point of view. Block copolymerisation deserves special interest in terms of the exceptionally wide potential utility of block copolymers obtained from comonomers with various functions. It should be noted, however, that the variety of comonomers that might be subjected to a random, alternating and block polymerisation involving a nucleophilic attack on the coordinating monomer is rather small. 

An interesting alternative is the chemical oxidation of heterocycles (e.g. thiophene or pyrrole) dissolved in an organic solvent (e.g. ethanol) on the surface of various materials. Conductive coatings (thickness 0.01 pm) can be produced on films of poly(phenylene sulfone), block copolymers of butadiene and styrene (Ultrason, Styrolux), poly(vinyl chloride), and other polymer films to give transparent, antistatic films with conductivities of about 0.001 S cm . Ceramics and glass can also be coated in this way. In addition, porous... 

This chapter is divided into two main parts polythiophene copolymers and polypyrrole copolymers. Each part reviews the random copolymerization of the heterocyclic monomer and important derivatives, principally those with substituents at the 3-position of thiophene and at the 1- and 3-positions of pyrrole. Alternating, block and graft copolymers are covered in both segments. Because applications of conducting polymers are reviewed in Volume 4, only applications unique to specify copolymers are covered here. In addition, a few theoretical studies dealing with conducting copolymers are reviewed. 

Although the majority of flame-resistant fibres are produced from fully aromatic and/or heterocyclic polymers, an alternative approach, based on utilization of crosslinked polymers, is also feasible. Phenol-formaldehyde fibres were produced by a process involving spinning of a fusible novolac resin followed by crosslinking of the precursor fibre. A recently developed nonflammable fibre with a low smoke-evolution is based on a copolymer of acrylic acid and acrylamide the carboxylic groups are crosslinked by zinc ions. ... 

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