Oxydianiline by Polycyclocondensation

Example 4.20 Preparation of a Polyimide from Pyromellitic Dianhydride and 4,4 -Oxydianiline by Polycyclocondensation 

Safety precautions Before this experiment is carried out, Sect. 2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

First Reaction (Stepwise Addition Polymerization) Preparation of the Poly(Amide Acid) 

0 g (0.02 mol) of 4,4 -oxydianiline (recrystallized from toluene and dried in vacuum for 8 h at 50°C) are dissolved in 30 ml of pure dimethylformamide in a dry 100 ml round-bottomed flask, fitted with a drying tube and magnetic stirrer. 4.36 g (0.02 mol) of pyromellitic dianhydride (sublimed in high vacuum) are added in portions over a period of a few minutes, with continuous stirring. The stepwise addition polymerization begins immediately and is completed by stirring the viscous solution for a further hour at 15 C. 

About 20 ml of the poly(amide acid) solution are then dropped into 300 ml of water with vigorous stirring. The precipitated colorless polymer is filtered with suction, washed several times with water, and dried in vacuum at lOO C for 20 min. The limiting viscosity number is determined in dimethylformamide at 25°C (Ostwald viscometer, capillary diameter 0.4 mm). 

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