The Synthesis And Properties Studies On A New Series Of Fluorinated Piperazine-functionalized Polyimides

For years, study on novel polyimides with improved properties have been much focus. According to the researches, the introduction of fluorinated groups can greatly improve solubility but reduce thermal performance. However, with the affect of hard group in molecule, PI with heterocyclic moieties obtain a excellent thermal-performance, while their solvency are not improved so well as fluorinated PI, In this paper, these two structures were introduced into molecule to prepare fluorinated piperazine-functionalized polyimides with excellent comprehensive performance.Studies have shown that the introduction of flexible chains (such as alicyclic structure) in the polyimide main chain can weaken the intramolecular and intermolecular charge transfer(CT), which reduces the dielectric constant of polyimide and improves their light transmittance and solubility.PI paint films possess excellent properties such as heat resistance, high strength, flexibility, aging resistance and radiation resistane, and show better dieleetric property even thinner than other insulating materials, which is favorable towards the miniaturization and light-weight of electronic machine. So, polyimides applied in the process of enameled wire is worthy of study.Specifically, the research in this thesis was mainly divided into four parts of work:In the first and second part of this paper, a new piperazine-containing diamine with trifluoromethyl pendent group,[1,4-bis(4-amino-2-trifluoromethylphenyl)] piperazine (BAFP) had been designed and synthesized as a potentially convenient condensation monomer to form piperazine-containing polyimides. Meanwhile, a new series of piperazine-containing polyimides were synthesized from the resulting diamine monomer with several aromatic dianhydrides by a two-step procedure, and the polyimides obtained were characterized in detail. Furthermore, to investigate the effect of trifluoromethyl substituents, the polyimides derived from BAFP were compared with analogous polyimides derived from a non-fluorinated piperazine -containing diamine monomer,[l,4-bis(4-aminophenyl)] piperazine (BAPP). The fluorinated polyimides exhibited good solubility in organic solvents. The glass transition temperatures andi nitial decomposition temperatures of FPI series were251-285℃and383-402℃.The modulus and tensile strengths of FPI series were3.4-6.79GPa and100-178MPa, exhibited excellent thermal and mechanical properties. In addition, the FPI series showed better dielectric property and higher optical transparency.In the third part, A novel alicyclic-functionalized diamine,1,1-bis[4-(4-amino-3-trifluoromethylphenoxy)phenyl]cyclopentane(BAFCP) and a novel alicyclic-functionalized dianhydride1,1-bis[4-(3,4-dicarboxylic anhydride benzoyloxy) phenyl] cyclopentane (BDAPCP) were synthesized from5-cholo-2-nitrobenzotrifluoride、 trimellitic anhydride acid chloride with1,1-Bis (4-hydroxyphenyl) cyclopentane.In the last part, a new interfacial compatibilizer was synthesized by silane coupling agent γ-ammonium propyl triethoxy silane(y-APS),4,4’-diamino diphenyl ether (ODA) and4,4’-oxydiphthalic anhydride (ODPA), and applied to the scene of enameled wire production. The thermal, mechanical and electrical properties of the obtained enameled wire were systematically investigated. The scrape resistance and breakdown voltage are obviously higher than the national standard of200class round enamel copper wire. The resulted enameled wire exhibited heat resistance, flexibility and adhesion properties.