Copolymers of polyacetylene

A number of block and graft copolymers of polyacetylene have been synthesized, generally with the idea of using the second half of the block as a solubilizing tail. In most cases, this modification rendmed the polymer soluble and has allowed a variety of studies of the 235 nor near2 . optical properties as weU as... 

Another approach to blending of polyacetylene with tough polymers is to form graft or block copolymers 280,281). Aldissi282) produced block copolymers by polymerizing acetylene at the ends of chains of anionic polyisoprene after conversion of... 

As discussed earlier, substitution onto the polyacetylene chain invariably has a deleterious effect on dopability and conduction properties. At the same time the stability tends to improve. Masuda et al.583) studied a large range of substituted polyacetylenes and found that stability increased with the number and bulkiness of the substituents, so that the polymers of aromatic disubstituted acetylenes were very stable, showing no reaction with air after 20 h at 160 °C. Unfortunately, none of these polymers is conducting. Deitz et al.584) studied copolymers of acetylene and phenylacetylene they found that poly(phenylacetylene) degrades even more rapidly than does polyacetylene and that the behaviour of copolymers is intermediate. Encapsulation of the iodine-doped polymers had little effect on the degradation, which is presumably at least in part due to iodination of the chain. 

Aldissi 586) has reviewed the stability of block copolymers of acetylene and other non-conducting blocks. The copolymers are somewhat more stable than polyacetylene but the effect is small. 

A variety of copolymers of acetylene and other alkynes have been prepared. Copolymers of acetylene and methylacetylene (86), a soluble polyene, were more tractable than polyacetylene itself, but as the fraction of methylacetylene in the copolymer increased, both the tractability and the final conductivity of the iodine-doped polymer decreased. At an acetylene mole fraction of 0.5, the copolymer was insoluble, and the final conductivity had fallen from greater than 100 to 1 S/cm. Some plasticization remained, however, and the polymer could be stretched to elongation ratios as high as 7. Copolymers of acetylene and phenylacetylene containing 26% acetylene were soluble in methylene chloride (24). Like methylacetylene copolymers. 

From a consideration of the defects in Figure 2 as they relate to the product structure in Scheme 2, it is possible to describe the mixed polyacetylene case as an alternating copolymer of AC CA and BCaCB, or a homopolymer of AC CB. The latter situation invites a synthetic experiment, that is, the attempted solid-state polymerization of N-(3-bromo-2-propynyl)carbazole (j0. We have isolated this compound in two polymorphic forms. Both forms are melt-stable, but undergo reaction upon exposure to soco gaituna radiation. Characterization of the reaction products has been initiated. 

In this paper, we wish to report two different types of elastomer blends, ethylene-propylene-diene terpolymer/polyacety-lene and styrene-diene triblock copolymer/polyacetylene, in the hope that the stability of polyacetylene might be improved by... 

The high level of interest in potential applications of polyacetylene (1), (CH)X, is tempered in many instances by the prospects of intractability and poor physical and mechanical properties. In an attempt to mitigate such undesirable characteristics, we have attempted to prepare copolymers and blends (or composites) in which the electroactive component is (CH)X. 

From the viewpoint of its molecular structure, PPV can be considered an alternating copolymer of the repeat units of polyacetylene and poly(p<7r<7-phenylene) (Figure 1.35). With respect to electronic structure, it is one of the simplest non-degenerate ground state polymers, and as such it is attractive for theoretical approaches. 

NBE and 7.8-bis(trifluoromethyl)tricyclo[4.2.2.0 ]-deca-3.7.9-triene may be used to generate ABA-triblock copolymers of NBE (A-block) and polyacetylene (B-block) via the Durham route ° ° (Scheme 39).354,355 -ppig poly-NBE blocks sufficiently solu-... 

Leung, L. M., and Tan, K. H. Synthesis and electrical properties of polyacetylene copolymers from poly(phenylvinyl sulfoxide) and its oxidized products. Macromolecules, 26, 4426-4436 (1993). 

Other copolymers of pyrrole including those of polypyrrole with polythiophene, polyphenylene oxide, and polyacetylene are discussed in Section IV.E. 

As reported by Krische and Ahlgren [213], the electrochemical polymerization of pyrrole on a polyacetylene anode produces a composite of polyacetylene and polypyrrole. Polypyrrole appears to form on the outer surface of polyacetylene at 1.0 V (versus SCE) when an electrode with neutral polyacetylene grown on it is immersed in an electrolyte of 0.1 M tetrabutylammonium tetrafluoroborate and 0.1 M pyrrole dissolved in acetonitrile. When doped polyacetylene was used, the pyrrole seemed to form on the polyacetylene fibrils, leaving a porous material similar to the original polyacetylene. In either case, the copolymers have conductivities approaching 40 S cm" and demonstrate increased stability in the presence of air and moisture compared to pristine poly acetylene. 

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