Polystyrene with narrow molecular weight distribution (Mw ≈ 4050 g/mol, PDI ≈ 1.06) is a specialty polymer primarily used as a calibration standard in analytical techniques such as gel permeation chromatography (GPC), size-exclusion chromatography, and light scattering for accurate molecular weight determination. Its precisely controlled and uniform molecular structure enables reliable instrument calibration and validation in polymer research labs. It is also utilized in academic and industrial R&D to investigate fundamental polymer properties, including solution viscosity, thermal behavior, and chain dynamics in unentangled regimes. Furthermore, this material serves as a precursor for producing uniform polystyrene microspheres applied in biomedical fields, such as flow cytometry, immunoassays, and drug delivery systems, where monodispersity ensures consistent performance.