Low Dielectric Polyetherimides Derived from Bis[4-(4-(4-aminophenoxy)-2-tert-butylphenoxy)phenyl] Sulfone and 4,4'-Bis[4-(4-aminophenoxy)-2-tert-butylphenoxy]perfluorobiphenyl

Two diamines, bis[4-(4-(4-aminophenoxy)-2-tert-butylphenoxy)phenyl] sulfone (PSNH₂) and 4,4'-bis[4-(4-aminophenoxy)-2-tert-butylphenoxy)perfluorobiphenyl (PFNH₂), were prepared from 3-tert-butyl-4-hydroxyanisole using a four-step procedure, including two nucleophilic substitutions, demethylation, and catalytic reduction. On the basis of PSNH₂ and PFNH₂, two series of low dielectric polyetherimides (PEIs) were prepared. Both series of PEIs exhibit moderate-to-high thermal properties, including a glass transition temperature (T _g) > 259 °C (depending on the rigidity of dianhydride), a 5 wt % decomposition temperature (T _d5%) > 496 °C, and a coefficient of thermal expansion < 66 ppm/°C. Because of the hydrophobic tert-butyl phenylene oxide structure, both series of PEIs show excellent dielectric properties, with a dielectric constant as low as 2.4-2.7. The structure-property relationship of both series of PEIs is discussed in this work.