Condensation polymerization of triphenylamine derivatives with paraformaldehyde

Triphenylamine derivatives, such as 4-tolyldiphenylamine (TDPA) and N,N′-diphenyl-N,N′-di-(4-methylphenyl)-1,4-phenylenediamine (PDA), were reacted with paraformaldehyde (FA) using p-toluenesulfonic acid catalyst to yield linear polymers. 1H-NMR and 13C-NMR spectra revealed that FA reacted exclusively at the p-position of triphenylamine derivatives, and TDPA and PDA units were linked not only by a methylene linkage but also by a methylene ether linkage. The PDA–FA polymer contained higher amount of methylene linkage as compared to TDPA—FA polymer. Additionally, the number of methylene ether linkage was increased with the concentration of paraformaldehyde. The glass transition temperatures of PDA–FA and TDPA–FA were at 204°C and 111°C, respectively. These polymers were soluble in conventional solvents such as chloroform, toluene, etc., and showed sufficient morphological stability after the film formation. The hole drift mobility of PDA–FA was found to be in the order of 10−6 cm2/V s.