A monomer, 3,3’-bis(4-fluorobenzoyl)biphenyl, was prepared in high yield in two steps from inexpensive 3-chlorobenzoyl chloride and fluorobenzene, and polymerized by nucleophilic displacement reaction with various bisphenol monomers in tetramethylene sulfone to produce a series of high molecular weight poly(aryl ether ketone)s containing 3,3’-dibenzoyIbiphenyl (DBBP) moieties. The spectroscopic, thermal, and thermomechanical properties of these polymers and related isomeric polymers having 2,2’- and 4,4’-DBBP units were determined and compared to study the effects of changes in the substitution pattern of the biphenyl unit. Except for the 2,2’-DBBP series of polymers, T(g)s were found to increase with increasing linearity of the DBBP unit. The 2,2’-DBBP series of polymers had exceptionally high T(g)s due to the sterically restricted motions in the biphenyl unit caused by the 2,2’-substitution. In addition, they also showed evidence for torsion within the 2,2’-DBBP unit, whereas in other isomeric polymers the DBBP units are believed to be relatively coplanar. Thermal stabilities and tensile moduli for these polymers proved to be independent of substitution patterns.