Transoid conformation polyacetylene

Percec and coworkers have shown that the oriented fibers of dendronized polyacetylenes can undergo thermally induced mechanical motion [38]. In this system (Figure 37.12), the dendrons around the polymer backbone become self-organized and thus facilitate a reversible ciscoid-to-transoid conformational isomerism of the polymer backbone. This isomerism is then converted into unidirectional macroscopic motion along the fiber axis. Remarkably, this mechanical motion could be used to displace objects with a mass of up to 250-fold that of the polymer fiber. 

Polyacetylene contains conjugated double bonds in a linear structure [51-54], which leads to special electrical conductivity properties. For this reason, polyacetylene and some other related polymers have applications in the optical and electronic industries. Pojyacetylene synthesized at relatively low temperature seems to have a cis-conformation, with two possible cis- forms indicated as c/s-transoid, and frans-cisoid, as shown below ... 

Stereoregular ds-transoidal polyacetylenes can take a regular helical conformation. The main-chain stereoregularity is important in inducing a single-handed helical conformation. Rhodium catalysts such as [Rh(norbor-nadiene)Cl]2 are often used to obtain a stereoregular polymer. The helical structure of polyacetylenes is... 

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