New hole transport polymers have been synthesized by condensation polymerization of 4tolyldiphenylamine (TDPA) with various types of aldehyde. The reaction conditions have been investigated to yield polymers with high molecular weight. It is found that the molecular weight and yield of the TDPA±aldehyde polymers strongly depend on the electron donor±acceptor nature of the substituent on the aromatic ring of the aldehyde monomer. Structural characterization by 1 H NMR spectroscopy shows that the addition condensation reaction occurs exclusively at the para position of TDPA. The electrochemical and optical properties of polymers have been investigated by cyclic voltammetry and UV±vis spectroscopy. Cyclic voltammograms of all polymers show well-de®ned pairs of reduction and oxidation peaks, indicating that the polymers are electrochemically active. All polymers show low conductivities of magnitude 10 À14 S cm À1 . Differential scanning calorimetry measurements reveal that TDPA±aldehyde polymers exhibit glass transitions in the range 170±230°C. These polymers possess good solubility and the ®lms show suf®cient morphological stability.
A series of different benzaldehydes-4-tolyldiphenylamine polymers has been oxidized by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetrachloro-1,4-benzoquinone (p-chloranil), and also doped by 10-camphorsulfonic acid in order to increase their conductivity. The doped polymers were characterized by 1 H NMR spectroscopy, cyclic voltammetry, UV, and IR spectroscopy. It was found by 1 H NMR spectroscopy that the oxidation yield increased with the increased amount of oxidation agent. It was shown that optical and electrochemical bandgaps of the polymers decreased after oxidation. Conductivity measurements revealed that the applied oxidation and doping procedure resulted in decreased electrical resistance of their initial polymers, down to the level of semiconducting materials. An increased thermal stability of the polymer after oxidation was confirmed by differential scanning calorimetry.
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