Adhesion property of novel polyimides with 1-[3?,5?-bis(trifluoromethyl)phenyl] pyromellitic dianhydride

Expanding the Scope of Electron-Deficient C-H Building Blocks: Direct Arylation of Pyromellitic Acid Diimide

Direct C-H activation of pyromellitic diimide (PMDI) is reported for the first time. The method avoids cumbersome pathways involving bromination usually required for further cross-coupling. Good to excellent yields of mono- and di-substituted PMDI derivatives can be obtained under optimized reaction conditions. The reaction scope was also explored, and the materials were characterized with respect to their thermal, optical, and electronic properties.

Synthesis of phthalic end-capped copolyimides and their adhesive properties

A series of molecular-weight-controlled aromatic copolyimides based on anhydrides 4,4′-oxydiphthalic anhydride (ODPA) or/and 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) were prepared by polycondensation reaction with mixture of diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and 4,4′-diaminodiphenylsulphone (DDS) in the presence of phthalic anhydride (PA) as end-capping agent. The effect of the chemical structure of the copolyimides on solubility, rheological behavior, thermal stabilities and adhesive properties was investigated. Experimental results suggested that the solubility and thermal properties of copolyimides could be improved by incorporation of asymmetric α-BPDA. The copolyimide TPI-B (α-BPDA/6FAPB-DDS/PA) exhibited better solubility with the solid content as high as 45 wt.% in N, N-dimethylacetamide and high thermal stability with the Tg of 306 °C. TPI-A (ODPA/6FAPB-DDS/PA) and TPI-C (α-BPDA-ODPA/6FAPB-DDS/PA) could be produced into glass-cloth-supported adhesive films. TPI-A adhesive film gave better adhesive properties at room temperature with lap shear strength of 16.41 MPa and T-peel strength of 2.1 kN m−1, which attributed to its flexible structure and good melt processability. TPI-C adhesive film exhibited higher adhesive properties at elevated temperature with the lap shear strength exceeding 9 MPa at 280 °C. The copolyimides with combination of rigid and flexible structures could afford good melt flow behavior and high thermal stability, which yielded good adhesive properties at high temperature.