Polyacetylene, early research

It should be pointed out that, despite this attention, 17 years after Shirakawa s discovery polyacetylene is not yet a commercial polymer, and many early research efforts at industrial laboratories have been discontinued. In part, progress has been hampered by the fact that polyacetylene, and most other unsubstituted conjugated polymers, can be neither dissolved nor melted. In addition, polyacetylene is unstable in air, complicating its incorporation into products. However, the diversity of potential uses for conjugated polymers, combined with the experimental challenges of preparing more tractable materials, has kept the field vibrant. 

In 1958, Natta and co-workers polymerized acetylene for the first time by using a Ti-based catalyst. This polymerization proceeds by the insertion mechanism like the polymerization of olefins. Because of the lack of processability and stability, early studies on polyacetylenes were motivated by only theoretical and spectroscopic interests. Thereafter, the discovery of the metallic conductivity of doped polyacetylene in 1977 stimulated research into the chemistry of polyacetylene, and now poly acetylene is recognized as one of the most important conjugated polymers. Many publications are now available about the chemistry and physics of polyacetylene itself. 

Active research of the electronic properties began in the early 1970s, when it was shown that polyacetylene may be synthesized as a flexible film with arbitrary and specially oriented fibrils. 

The materials used in most current research are irregular mats of highly crystalline fibrils with diameters of around 10 nm, so that the films are characterised by a very high surface area (around 60 m2 g-1), a problem in some potential applications and an asset in others. The morphology of polyacetylene is sensitive to the conditions of preparation and to ageing and was the subject of much heated discussion in the early development of polyacetylene. 

From the beginning of their history in the late 1970s, conductive polymers (organic metals) have been considered as intractable and insoluble. It was an important goal in basic research as in application-oriented materials science to develop techniques by which they could be processed. The use of solvents was one of the options. As early as 1983-84, after five years of research, we happened to create the first clear dispersions of polyacetylene, polypyrrole, and polyaniline [42], with and without the presence of conventional polymeric binders. This was the beginning of nanotechnology with organic metals. 

Many conducting polymers and their derivatives or composites have been investigated. Early conducting polymers, such as polyacetylene, suffer from instability in air and were difficult to prepare [59]. Extensive research has yielded several promising polymers and their derivatives, including polyanilines, polypyrroles, and polythiophenes [52, 59], specifically for biomedical applications [54, 60]. 

Soon after the discovery of conducting polyacetylene attempts to utilize these exciting new compounds in technical applications started. " Bayer s Central Research Department also initially focused on polyacetylenes beginning as early as 1980. Several promising attempts to stabilize polyacetylene in its highly doped form and to achieve processability ultimately failed. As a result, Bayer rather promptly decided to abandon this research direction. Attempts to utilize polyacetylene in polarizers several years later failed commercially. 

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