Abstract
Polyimides (PIs) possess excellent thermal and mechanical properties, but their poor solubility in organic solvents restricts their utility. Numerous studies have focused on improving PI solubility by weakening inter-molecular interactions within the polymer. The polyimide composed of aromatic anhydride, 6,6′-(hexafluoroisopropylidene)dipthalic anhydride and aromatic diamine, 4,4′-oxidianiline, is known to be soluble, but solubility at room temperature is very limited. In this study, a soluble polyimide copolymer, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (Bis-ap-af), a diamine containing hydroxyl groups, was incorporated into the above-mentioned PI via chemical and thermal imidization. Chemical imidization resulted in the acetylation of the hydroxyl groups of Bis-ap-af units, while the hydroxyls remained intact under thermal imidization conditions. The acetoxy-containing soluble polyimide copolymers displayed improved solubility in a number of organic solvents compared to the conventional PI, and the copolymer films maintained their mechanical properties and presented reduced yellowness.
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