Effect of di‐halogen monomers embraced in main chain of low‐dielectric colorless fluorene‐based poly(aryl ether)s on their performance

Abstract Di‐halogen monomer structures play crucial roles in determining the combined properties of high‐performance poly(aryl ether)s for microelectronic applications. In order to disclose such relationship in detail, 9,9‐bis(4‐hydroxyphenyl) fluorene (BHF) was utilized to polymerize with various di‐halogen monomers, bearing phenyl‐1,3,5‐triazine, ketone, sulfone, nitrile, diketone moieties. Through solution nucleophilic substitution polymeri‐zation, a series of linear poly(fluorenyl aryl ether) (PFEX) was prepared. FTIR, 1 H‐NMR were resorted to confirm the polymer structure. PFEXs with high molecular weight exhibited a combination of excellent properties. Poly(fluorenyl aryl ether phenyl‐s‐triazine) (PFEP) and poly(fluorenyl aryl ether sulfone) (PFES) showed low dielectric constant of 2.59 and 2.43, respectively. Representatively, PFEP with T d5% value as high as 561 °C and T g up to 302 °C showed high light transmittance (86.94%), and tensile strength up to 91 MPa. Based on free volume calculation by molecular dynamics method, it was found that rigid and bulky structures, such as phenyl‐1,3,5‐triazine and sulfone groups, were proved to be beneficial for polymer thermal performance along with the dielectric property and light transparence. Robust polar group, for instance nitrile group, contributed more to thermal resistance, however, negatively affected the dielectric property. This work provide commendable suggestions for di‐halogen monomer selection for future low‐dielectric poly(aryl ether) developments.