1,2,4,5-Benzenetetra acyl chloride (BTAC) was prepared from pyromellitic anhydride and phosphoric chloride. The behavior in interfacial polycondensation of 4,4′-methylene dianiline (MDA) or ethylene diamine (EDA) in water with BTAC in dichloromethane with tetrabutyl ammonium chloride (TBAC) as the catalyst was examined with Fourier transform infrared spectroscopy (FTIR), fast atom bombardment mass spectroscopy (FABMS), and scanning electron microscope (SEM). A heat-resistant film can be obtained by successive heating of the resulting thin films.
Because BTAC is a tetrafunctional compound with high reactivity, the interfacial reaction is a competitive reaction of hydrolysis and amidation among the reacting groups. The optical density of FTIR spectra was employed for calculating the percentage of hydrolysis. The hydrolysis is suppressed when (1) the temperature is decreased, (2) sodium carbonate is added, (3) the proportion on the concentration of diamine is increased relative to the concentration of BTAC, (4) the diamine solution is agitated, and (5) TBAC is added to the diamine (as).
The percentage of hydrolysis can be controlled at will, e.g., 50%. A high-resistant polyimide can be prepared through thermal treatment in a nitrogen atmosphere. By increasing the concentration of the reactants or using a good sovlent, the film obtained is thicker, but in our system, the maximum thickness of the film seldom exceeded 20 pm.