Preparation and Characterization of Head-to-Head Polymers 1331 of an amide linkage and a tetrahydropyran ring along the chains. Possible molecular arrangements providing all hydrogen bonds are ideally regularly formed between polymer chains are illustrated in Figure 7. In the presence of water hydrogen bond interactions must exist between the water molecules and the amide groups. The ring ether oxygens may also interact with the water molecules.Poly(BOL) film has been found to exhibit some extent of permeability and permselectivity for alkali metal ions in water. Further work is in progress on the properties of poly-(BOL) and will be published in the near future.Acknowledgment. Thanks are given to Mr. M. Ito for his help in the experimental work.References and Notes U) . K.

Differential pulse polarography (DPP) and cyclovoltammetry (CV) were conducted to study the redox behaviour of poly@-phenylenevinylene) (PPV; EY = 0,76 V; ETd = -1,74 V) as well as of three insoluble PPV-derivatives and four soluble aryl-substituted PPV's. Oxidation studies of DP-PPV, DMOP-PPV and DPOP-PPV in comparison with two series of the oligomeric model compounds la-e and 2a-d lead to the conclusion that for DMOP-PPV (E"" = 0,98, 1,24, 1,3 1 V) and DPOP-PPV (P" = 1 ,lo, 1,29, 1,44 V) three distinct oxidation stages exist, which are reversibly occupied and represent 1/2, 1 and 2 positive charges per repeating unit. In DP-PPV two oxidation stages representing 1/2 and 1 positive charges were found to be reversibly occupied (P" = 1,17, 1,69 V), whereas at higher potentials irreversible dehydrocyclization occurred. part 39: cf. ref. ')

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Friedrich-Schiller-Universitat J e n a , S e k t i o n Chemie H u m b o l d t s t r a a e 1 0 , 6900 J e n a , German Democratic R e p u b l i c

The development of PPV systems has moved from intractable powders to flexible films. This opens new uses as thin film insulation material, as photoconductive electrophotographic recording material, and as novel electrochemical electrode material for polymer batteries. Tractable films were readily achieved either by transformation of a soluble precursor polymer or by introduction of solubilizing phenyl substituents. Contrary to wide‐spread expectations PPV is not a metal‐like conductor, but rather a broad‐band gap photoconductor (Eg = 2,4 eV). However, it can be made highly conducting upon appropriate chemical or electrochemical treatment, thus forming several salt‐like redox stages (σ = 10−4 to 103 S/cm). The formation of coexisting polymeric ion radicals (polarons) and diions (bipolarons) is well understood in terms of the concept of chain segment redox reactions (ECS concept). More detailed studies of the phenyl substituent effect show that the electronic properties are not altered drastically, but are modified due to broadening the band gap up to 2,9 eV along with an increase of the oxidation potential. Furthermore, phenyl substitution increases the resistance to heat, and stabilizes the deeply coloured redox stages.