Structure and Properties of Low Dielectric Constant Polyetherimide Films Containing-CF3 and Cardo Groups

Cardo containing phenoxy and -CF3 derivate diamine was synthesized, and further it was polymerized with 3,3',4,4'-biphenyl tetracarboxylic dianhydride to prepare polyetherimide containing Cardo group. The transmittance of the prepared polymer increased from 82% to 88% and the dielectric constant decreased from 2.91 to 2.83 with a slight decline in thermal and mechanical performance when -CF3 was introduced. The molecular simulation in terms of charge distribution, electric potential energy, chain stiffness and aggregation state revealed that -CF3 could restrain charge transfer and decrease the unit dipole moment and polarization for its larger volume. The optical and dielectric performance was significantly enhanced, but the thermal and mechanical performance decreased slightly when the -CF3 group was introduced. The glass transition temperature of the polymer declined from 329 degrees C to 311 degrees C. The investigation conducted in this paper can offer valuable reference to the optimization and development of synthesis and comprehensive performance of polyimide.