The linear viscoelasticity and molecular structure of a series of poly(4-vinylbiphenyl) (PVBP) samples with polydispersities ranging from 1.08 to 2.75 are investigated using wide-angle X-ray scattering (WAXS), small-angle neutron scattering (SANS), and rheological measurements. PVBP chain dimensions, such as statistical segment length, persistence length, and packing length, are obtained from SANS measurements. Because of the bulkiness of the biphenyl monomer, PVBP has the lowest chain flexibility and the largest reptation tube diameter among most common thermoplastics, including polystyrene and polyvinylcyclohexane. Nevertheless, PVBP follows the universal power law dependence between elastic modulus and packing length (GN0 ∝ p–3). X-ray diffraction of PVBP consist of two main amorphous peaks: one associated with the interchain (backbone) correlations and a second one arising from phenyl–phenyl correlations. The latter are due to π–π stacking of the phenyl rings, mostly arranged in the T-shaped configura...