Synthesis of new diacid monomers and poly(amide-imide)s: study of structure–property relationship and applications

Thermoplastic and soluble co-polyimide resins fabricated via the incorporation of 2,3,3′,4′-biphenyltetracarboxylic dianhydride

A series of co-polyimide (co-PI) resins with distorted noncoplanar structure were carefully designed and successfully fabricated by copolycondensation of 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydianiline (ODA), and 4,4′-(1,3-phenylenedioxy)dianiline (TPER). As-introduced asymmetric structure endowed these co-PI resins with excellent solubility and relatively low melt viscosity. Molecular simulation and dielectric analysis confirmed that the distorted noncoplanar structure induced a large amount of free volume. The minimum melt viscosity of co-PI resins decreased with increasing TPER content and reached 520 Pa·s at 400°C, indicative of good processability. Besides, the co-PI resins displayed outstanding thermal performance with glass transition temperature ranging from 256°C to 330°C and 5% weight loss temperature higher than 550°C in nitrogen atmosphere. Moreover, the co-PI sheets prepared by compression molding possessed tensile strength of 79.5–91.7 MPa and bending strength of 71.0–81.2 MPa when tuning the TPER/ODA ratio, with lower strengths observed at higher TPER content.

Tristable data storage device of soluble polyimides based on novel asymmetrical diamines containing carbazole

Two novel soluble aromatic polyimides were prepared from BBCDA and TFDMC by polycondensation with PMDA and BPDA via a two-step procedure. Memory devices were fabricated with the PIs. In the devices, ITO was used as the ground electrode (the cathode) and Al was set as the top electrode (the anode).

Synthesis of diol monomers and organosoluble fluorinated polyimides with low dielectric

Four diimide–diol monomers were synthesized from 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride and aminophenol/aminonaphthol. The structures of the monomers were characterized by spectroscopic analysis. A series of fluorinated polyimides (FPI-1 to FPI-8) were synthesized from these new diols and 4,4′-difluorobenzophenone/4,4′-dichlorodiphenyl sulphone, through nucleophilic displacement reaction. The FPIs were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, X-ray diffraction, thermogravimetry, differential scanning calorimetry, solution viscosity, solubility test, and dielectric properties test. FPIs were amorphous and showed good solubility due to the presence of >C(CF3)2 unit and flexible groups in the polyimides backbone. These FPIs also showed good thermal stability and the 10% weight loss occurred in the range 353–505°C. The limiting oxygen index values of FPIs were in the range of 31.5–39.1 and such FPIs can be used as self-extinguishing polymers. These FPIs have a dielectric constant in the range of 3.10–4.23 and can be used as high temperature electrical insulation materials.

Silarylene-containing oligo(ether-amide)s based on bis(4-(4-amino phenoxy)phenyl)dimethylsilane. Effect of the dicarboxylic acid structure on some properties

Inherent viscosity and MALDI-TOF analyses suggest the formation of oligomeric chains with sequences A–B, (A–B)₂ and (A–B)₃. The properties and therefore the eventual applications of these materials are modulated by the flexibility and the aromatic content of the chains.