Abstract:A novel aromatic diamine monomer, 4-(4-(1-pyrrolidinyl)phenyl)-2,6-bis(4-(4-aminophenoxy)phenyl)pyridine (PPAPP) containing pyridine rings, pyrrolidine groups, and ether linkages, was successfully synthesized using 4-hydroxyacetophenone and 1-chloro-4-nitrobenzene as starting materials by three-step reactions, and then used to synthesize a series of polyimides by polycondensation with various aromatic dianhydrides via a two-step method. The structure of PPAPP was characterized by NMR, FT-IR, and mass spectrometry analysis methods. These polymers showed good solubility in common organic solvents (e.g., NMP, DMF, DMSO, and DMAc) at room temperature or on heating. Moreover, they presented a high thermal stability with the glass transition temperature (T g s) exceeding 316 • C, as well as the temperature of 10% weight loss ranged from 552 to 580 • C with more than 67% residue at 800 • C under nitrogen. Furthermore, they also exhibited excellent hydrophobicity with a contact angle in the range of 85.6 • -97.7 • , and the results of Wide-Angle X-ray Diffraction (WAXD) indicated that all of the polymers revealed an amorphous structure.

A novel aromatic diamine monomer, 4-(3,5-dimethoxyphenyl)-2,6-bis(4-aminophenyl)pyridine (DPAP) was successfully synthesized by 4 0 -nitroacetophenone and 3,5-dimethoxybenzaldehyde as raw material. The structure of DPAP was confirmed by Fourier transform infrared, nuclear magnetic resonance, and mass analysis. A series of polyimides (PIs) were obtained by polycondensation with various dianhydrides via the conventional two-step method. These PIs showed good solubility in organic solvents. They also presented high thermal stability, the glass transition temperatures (T g ) of polymers were in the range of 325-388 8C, and the temperature at 10% weight loss was in the range of 531-572 8C. Furthermore, these polymers also exhibited outstanding hydrophobicity with the contact angles in the range of 89.18-93.58. Moreover, the results of wide-angle X-ray diffraction (WAXD) confirmed these polymers showed amorphous structure.

A series of novel fluorinated polyimides (PIs) were prepared from 4-(3,4-difluorophenyl)-2,6-bis(4-aminophenyl)pyridine (FPAP) and commercial aromatic dianhydrides via conventional two-step thermal imidization technique. The structure of the monomer was confirmed by FT-IR, NMR, and mass spectrometry. All of the obtained PIs were studied with FT-IR, TGA, DSC, WAXD and contact angles analysis. These results showed that polymer materials presented excellent thermal properties with the glass transition temperature (T g ) in the range of 336-434 ℃, as well as T 5% , and T 10% decomposition temperature ranges of 543-600 ℃ and 562-622 ℃ in a nitrogen atmosphere, respectively. Moreover, they presented excellent mechanical properties with tensile strengths of 68-91 MPa, elongation at break of 5.6%-10.2%, and young's modulus of 1.8-2.4 GPa. Furthermore, they showed outstanding hydrophobicity with the contact angle in the range of 90.5°-96.6°, and the results of WAXD indicated all of the polymers presented amorphous structure.