Polyethylidenes

Polyethylidene Peroxide. See under Ethyli-deneperoxide, Polymeric in Vol 6, E306-R... 

The contrast between formulas 20 and 21, both pertaining to isotactic polyethylidene, should be noted This contrast occurs because the polymer repeating unit has only one carbon atom in the chain and thus there is no correspondence between such periodicity and that of the zigzag representation. The classical definition of an isotactic polymer (as one in which all substituents are on the same side of the chain) holds true, in general terms, only if the polymer is represented in the Fischer projection. Analogous considerations pertain to syndiotactic polyethylidene 22 and 23. 

The first extensive lUPAC publications on stereochemistry in high polymers were published in the early 1960s, and subsequently in 1966 as a single article (39). In addition to more conventional polymer names, eg, polyethylidene and polypropylene, the -amer nomenclature was introduced in 1952 (10). lUPAC basic definitions relating to stereochemistry, eg, tacticity and isotactic polymer, were published in 1974 (1). 

Some measurements of this property have been made in a range of electrically conducting polymers. These include epoxy resin/polyaniline-dodecylbenzene sulfonic acid blends [38], polystyrene-black polyphenylene oxide copolymers [38], semiconductor-based polypyrroles [33], titanocene polyesters [40], boron-containing polyvinyl alcohol [41], copper-filled epoxy resin [42], polyethylidene dioxy thiophene-polystyrene sulfonate, polyvinyl chloride, polyethylene oxide [43], polycarbonate/acrylonitrile-butadiene-styrene composites [44], polyethylene oxide complexes with sodium lanthanum tetra-fluoride [45], chlorine-substituted polyaniline [46], polyvinyl pyrolidine-polyvinyl alcohol coupled with potassium bromate tetrafluoromethane sulfonamide [47], doped polystyrene block polyethylene [38, 39], polypyrrole [48], polyaniline-polyamide composites [49], and polydimethyl siloxane-polypyrrole composites [50]. 

The first definition of an isotactic polymer was made with reference to a zig-zag planar conformation. Take, however, the case of polyethylidene the isotactic polymer will be represented, in the modified projection, as foilows ... 

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