Highly Transparent Aromatic Polyamides from Unsymmetrical Diamine with Trifluoromethyl Groups.

Soluble and transparent wholly aromatic polyamides (PAs) were synthesized from an unsymmetrical diamine monomer having trifluoromethyl (CF3) groups, 4-(4'-aminophenoxy)-3,5-bis(trifluoromethyl)aniline. The monomer was polymerized with several dicarboxylic acid monomers via the Yamazaki-Higashi polycondensation method. All of the synthesized polyamides have an amorphous morphology, and they are soluble in many polar organic solvents at room temperature. Flexible and transparent films of the polyamides were prepared by solution casting and these polymer films show good optical transparencies with cut-off wavelengths of 337-367 nm and transparencies of 88%-90% at 550 nm. In addition, all the polymers were thermally stable over 400 °C and exhibited glass transition temperatures (Tg) higher than 300 °C. Unsymmetrically inserted trifluoromethyl groups on polyamides improves the solubility as well as the transparency of the polymers while maintaining good thermal properties. They also showed low refractive indices around 1.5333~1.5833 at 633 nm owing to the existence of low polarizable trifluoromethyl groups.

Synthesis of Arylene Ether-Type Hyperbranched Poly(triphenylamine) for Lithium Battery Cathodes.

We synthesized a new poly(triphenylamine), having a hyperbranched structure, and employed it in lithium-ion batteries as an organic cathode material. Two types of monomers were prepared with hydroxyl groups and nitro leaving groups, activated by a trifluoromethyl substituent, and then polymerized via the nucleophilic aromatic substitution reaction. The reactivity of the monomers differed depending on the number of hydroxyl groups and the A2B type monomer with one hydroxyl group successfully produced poly(triphenylamine). Based on thermal, optical, and electrochemical analyses, a composite poly(triphenylamine) electrode was made. The electrochemical performance investigations confirmed that the lithium-ion batteries, fabricated with the poly(triphenylamine)-based cathodes, had reasonable specific capacity values and stable cycling performance, suggesting the potential of this hyperbranched polymer in cathode materials for lithium-ion batteries.