Formation of honeycomb films based on a soluble polyimide synthesized from 2,2′-Bis [4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride and 3,3′-dimethyl-4,4′-diaminodiphenylmethane

A soluble polyimide was synthesized from 2,2′-bis[4-(3,4- dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and 3,3′-dimethyl-4, 4′-diaminodiphenylmethane (DMMDA) by a two-step method, and it had good solubility both in strong bipolar solvents and in common low-boiling-point solvents. The BPADA-DMMDA polyimide was dissolved in chloroform (CHCl ₃) and cast onto a glass sub-strate in a humid atmosphere. The BPADA-DMMDA/CHCl₃ solution easily formed honeycomb films. Some affecting factors, such as the polymer solution concentration, atmospheric humidity, and solvent volatility, were tested.