Differential reactivity of aromatic diamines during polyimide formation in water

A series of mono and di-imide compounds were synthesized by the reaction of common aromatic diamines with 4,5-dichlorophthalic acid in aqueous solution (at temperature between 160 °C and 200 °C) as a precursor to determining the chemical reactivity changes in these diamines during copolyimide synthesis under the same conditions. The reactivities of the second amino group were shown to reduce dramatically, in number of examples, after substitution had occurred on the first amino group. The effect of these reactivity changes on polymer and copolymer properties was examined by the synthesis of a series of polymers containing two of the diamines with very different reactivity behaviours.The model compounds and polymers were characterized by FTIR, ¹H NMR and where possible by mass spectroscopy. The polymers were also characterized by GPC, Tg and some mechanical properties.