Average number of monomer repeat units n Refractive index ρ Mass density (gm/mL) R Molar refraction (ml/mol); RM for the monomer repeat unit; RS for the solvent RGD Gladstone-Dale molar refraction (ml/gm); RGD,M for the monomer repeat unit; RGD,S for the solvent RLL Lorentz-Lorenz ...