Acetylene, copolymers

Polymer synthesis by step-reaction involves the coupling of small molecules which are difunctional by virtue of having two reactive functional groups. It is common for the coupling to involve elimination of a small molecule, and typical examples might be the synthesis of a polyester from a hydroxy-acid or of a polyamide by reaction of a diamine with a diacid. Step-reaction polymerizations are often equilibria, whereas chain-reaction polymerizations are more usually irreversible. 

In principle, it should be possible to prepare polyacetylene and its derivatives by coupling reactions of appropriately 1,2-substituted olefins. In practice this route does not appear to have been explored and step-reactions have mostly been applied to prepare aromatic and heteroaromatic polymers. Some of the more important syntheses ae reviewed below others have been reviewed by Feast29). 

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They can be used to initiate the polymerization of monomers on several centres simultaneously, i. e. for the preparation of star polymers. Delocalized carbanions of a different type are formed by the deprotonation of acetylene copolymers [198]... 

The properties of such apparently soluble materials differed greatly from those containing stabilized polyacetylene crystallites. Attempts to dope the soluble copolymers yielded materials with low conductivities, and chemistry typical of solution chemistry (bromination) was observed rather than the formation of a stable bromine-doped polyacetylene phase. A poly(isoprene-fo-acetylene) copolymer oxidized with iodine gave conductivities as high as 1-10 S/cm, but the characterization of the copolymer was insufiScient to unambiguously identify it as a soluble copolymer. On the basis of previously reported work, this material is likely to correspond to a stabilized suspension rather than a solution. 

The metathesis copolymerization of the cyclobutene derivative, 7,8-bis(trifluoro-methyl)tricyclo[4.2.2.0 ]deca-3,7,9-triene (MO (7 in Ch. 13), with norbomene or cyclopentene (M2) gives copolymers that are readily converted into acetylene copolymers by elimination of l,2-bis(trifluoro)benzene from the Mi units, but the compositional sequence distribution in these copolymers is difficult to establish (Ramakrishnan 1989b). 

The morphological structure of the butadiene-acetylene graft copolymer films was studied using TEM, electron diffraction and wide-angle X-ray scattering (WAXS). A series of the butadiene-acetylene copolymers with acetylene content ranging from 10 to 50 wt% and a cisitrans ratio from 70/30 to 10/90 was prepared [73]. Unreacted polybutadiene homopolymer was extracted from the copolymer samples in toluene... 

Two basic approaches that can be used to prepare random or non-segmented acetylene copolymers are (1) using mix monomers during synthesis and (2) postpolymerization chemical modification. The earliest method used to prepare random copolymers of... 

In addition to the various experimental techniques used to determine and verify the electrical and electronic properties of conductive acetylene copolymers, a number of theoretical calculations and models have also been adopted for the prediction and explanation of the observed electrical properties. The density of... 

A second group of polyaromatic polymers have also been studied These include poly(phenylene vinylene) (15), which may be considered an acetylene copolymer, and its derivatives these polymers are dopable to conductivities up to 3 s/cmj Poly(2,5-thienyltye) (16) yields a conductivity of 10 s/cm with iodine Recently poly(N-methyl-3,3 -carbazolyl (17) was synthesized and upon treatment with iodine yielded a conductivity of 1 s/cm. Polymers (18) containing phenylene and sulfur nitride linkages are able to yield relatively high conductivities upon oxidation ... 

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