Synthesis and characterization of fully aliphatic polyimides from an aliphatic dianhydride with piperazine spacer for enhanced solubility, transparency, and low dielectric constant

Article abstract of DOI:10.1002/pola.27242

A new series of fully aliphatic polyimide (API) based on a novel aliphatic dianhydride monomer-2,2-(1,4-piperazinediyl)-disuccinic anhydride (PDA), in which two units of succinic anhydride have been connected by an aliphatic heterocyclic piperazine spacer that possesses aminomethylene (-NCH₂) moiety in the aliphatic/alicylic backbone capable of inducing charge transfer (CT) interactions in the polyimide network, was successfully synthesized. The APIs were soluble in common polar organic solvents. The polyimide films of PDA with alicyclic diamines were almost colorless. T₁₀ (temperature of 10% weight loss) of APIs were ranged from 299-418 C and T_g of API3-API6 were in the temperature range of 170 to 237 C. The light-colored polyimide films of API3-API6 possessed good mechanical properties with tensile strength of 54-72 Mpa, tensile modulus of 1.6-2.3 Gpa and elongation at break of 4-9%. The polyimide films of API3-API6 were highly flexible and free-standing which is quite rare in fully APIs. The dielectric constant of one of the synthesized API (API4) was as low as 2.14.