Melt polycondensation of bibenzoate dimethyl esters with ethylene glycol enabled the synthesis of polyesters containing linear (4,4′-bibenzoate (4,4′BB)) and kinked (3,4′bibenzoate (3,4′BB)) repeating units. Novel 3,4′BB:4,4′BB (co)polyesters with ethylene glycol (EG) showed an onset of weight loss (T d,5% ) above 350 °C. 1 H NMR spectroscopy confirmed 4,4′BB:3,4′BB incorporation, and size exclusion chromatography (SEC) revealed high molecular weights. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed glass transition temperatures (T g ) approaching 121 °C, crystallization and melting transition temperatures (T c and T m ), and sub-T g β-relaxations. 4,4′BB incorporation below ∼45 mol % afforded an amorphous morphology, while 4,4′BB incorporation above 45 mol % induced crystallinity. Melt rheology elucidated the effect of structure on flow behavior, and time−temperature superposition (TTS) revealed distinct flow transitions. TTS analysis also provided insight into the structural influence of regioisomers on fractional free volume (f g ) and flow activation energies (E a ). Incorporation of the symmetrical 4,4′BB monomer negligibly affected the f g but imparted a stiffer overall chain, resulting in higher E a . Positron annihilation lifetime spectroscopy (PALS) of the (co)polyesters confirmed a lack of change in free volume through measuring the average free volume of a spherical hole. Determination of oxygen permeability offered fundamental understanding of the relationship of monomer symmetry with gas permeability and free volume in unoriented films; kinked 3,4′BB monomer afforded higher overall barrier in amorphous films. Finally, tensile testing elucidated Young's moduli and yield strengths, confirming (co)polyesters' mechanical similarity to BPA-polycarbonate. Moduli ≤2.7 GPa and yield strengths up to 74 MPa confirmed BBbased (co)polyesters enhanced properties compared to other high-T g polyesters.