The role of molecular volume and the shape of the hole transport molecule in the morphology of model charge transport composites

We present a study of the morphology and molecular interactions in a model charge transport composite with 1,1-bis(di-4-tolylaminophenyl) cyclohexane (TAPC) as the hole transport molecule in bisphenol-A polycarbonate (BPAPC) and cyclohexyl polycarbonate, also known as bisphenol-Z polycarbonate (PCZ). Solution NMR shows that while there is aromatic interaction between the phenyl groups of the polycarbonate and TAPC, the broadening of the peaks corresponding to the latter indicates a decrease in the rotational motion. FTIR spectroscopy also exhibits frequency shifts of the aromatic C–H absorption peaks, which parallels the extent of the depression of the glass transition temperature (Tg) of the polycarbonate. These are compared with the previous results for N,N-diphenyl-N,N-bis(3-methylphenyl)-[1,1-biphenyl]-4,4-diamine (TPD) and tri-p-tolylamine (TTA), and the differences are rationalized on the basis of the molecular shape and van der Waals volume of the small molecules. It is proposed that when the polyc...