Poly -polyacetylene structure, preparation

Polypropylene amines, poly(amidoamines) (PAMAM) and silicon dendrimers set records for the number of generations, whereas the polyacetylene dendrimer prepared by Moore et al. [6] with the formula C1398H1278 and a mass of 18079.53 holds the heavyweight championship title of pure hydrocarbons. Mullen et al. have recently published a series of aromatic hydrocarbon dendrimers consisting of phenylene-bridged benzene rings. [7] Interestingly, these species form two-dimensional planes rather than three-dimensionally extended structures. 

A fairly obvious variant of the structures discussed so far v ould be to include both vinylene and phenylene units in the polymer backbone, and a considerable number of such structures have been investigated. The parent of this group of polymers is poly(paraphenylene vinylene), which has been prepared by a number of different routes. Like polyacetylene and poly(paraphenylene), this polymer is insoluble and difficult to process again the most promising synthesis appears to be that proceeding via a processable precursor (see Figure 4.7). In this case the precursor polymer is a polyelectrolyte which can be processed via standard solution techniques and converted to the required product as and when desired. 

The inherent insolubility and infusibility of polyacetylene coupled with its sensitivity to air imposes a barrier to the processibility of the polymer. As a result, considerable efforts have been directed toward obtaining polyacetylene from workable, easily processible polymers by means of polymer analogous transformations. In particular, the synthesis of polyacetylene from the dehydrohalogena-tion of poly(vinyl chloride) has attracted a lot of attention but the polymers prepared by this route generally possess relatively short conjugated segments and contain structural defects and cross-links [198,199],... 

Thermosensitive, and amphiphilic polymer bmshes optically active polymers consist of helical poly(iV-propargylamide) main chains and thermosensitive poly(iV-iso-propylacrylamide) (PNlPAm) side chains, were prepared via a novel methodology combining catalytic polymerization, atom transfer radical polymerization (ATRP), and click chemistry. The characterization of GPC, FT-IR, and H-NMR measurements indicated the successful synthesis of the novel amphiphilic polymer brashes. For the confirmation of helical structure of the polymers backbones and the optical activity of the final brashes used UV-Vis and CD spectra. The polymer with optically active cores (helical polyacetylenes) and thermosensitive shells (PNlPAm) brashes self-assembled in aqueous solution forming core/shell structured nanoparticles [137]. 

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