Sterically Encumbered Fluorene-Based Poly(arylene ether)s Containing Spiro-Annulated Substituents on the Main Chain

Two novel fluorene-based bisphenol monomers containing spiro-annulated substituents on the middle biphenylene moiety have been synthesized in this study. Through reacting with four 2-trifluoromethyl-activated bisfluoro monomers, two monomers were converted into a series of fluorene-based poly(arylene ether)s by nucleophilic displacement of the fluorine atoms on the terminal benzene ring of bisfluoro monomers. The obtained polymers exhibit weight-average molecular weight up to 2.41 × 105 g/mol in GPC. Thermal analysis studies indicated that these polymers did not show melting endotherms but did show ultrahigh Tg values up to 356 °C in DSC and outstanding thermal stability up to 643 °C for 5% weight loss in TGA under nitrogen atmosphere. The polymers are soluble in a wide range of organic solvents, THF, CHCl3, NMP, DMAc, DMF, toluene, etc., and are insoluble in DMSO and acetone at room temperature. Transparent and flexible films were easily prepared by solution casting from chloroform solution of each of the polymers.