Preventing gelation in polyisoimide synthesis

Studies of Thermal Imidization Kinetics of Polyisoimide Based upon 4,4′-[1,4-Phenylenebis-(1-methyl ethylidene)] Bisaniline and 4,4′-Oxydiphthalic Anhydride in Solid State

“…To the synthesized polyamic acid solution, 0.0733 g (0.4949 mmol) of phthalic anhydride was added and allowed to react for next 12 h in order to end-cap the amine end groups of polyamic acid. As reported previously [3], endcapping the amine groups of polyamic acids is critically important for preventing gelation during the dehydrocyclization step in polyisoimide synthesis. To the polyamic acid solution 6.2410 g (30.2477 mmol) of dicyclohexylcarbodiimide was added with stirring and the reaction mixture was stirred for 12 h at room temperature.…”

“…Conversion of polyamic acids to polyimides, however, leads to generation of water, which in turn causes the formation of voids or pin holes in laminates and in adhesive joints. In an effort to eliminate these drawbacks, polyisoimides, which can be converted to polyimides without formation of water, have been utilized as precursors for polyimides [3][4][5][6]. Thermal imidization of polyamic acids both in solid and in solution states have been studied by many investigators [7][8][9].…”

Synthesis and properties of acetylene-terminated isoimide and imide oligomers exhibiting excellent solubility behaviors in low boiling point solvents

“…7,17,18 A class of isoimide oligomers featuring a lower melting point and wider solubility range than the analogous imide oligomers has been reported and can be found in a variety of patents. [19][20][21] Kurita et al 17 have published detailed studies on the structural property influences of model polyisoimides and a facile synthesis of polyisoimides. Meanwhile, Mochizuki et al 22 and Senio et al 23 have developed a new photosensitive polyimide precursor based on polyisoimide.…”