© 2022In this study, thermodynamic properties, glass transition temperature and isomer separation ability of PVBC (poly (vinyl benzyl chloride)) -Diethanol amine (PVBC-DEA) polymer was investigated by IGC method. For purpose, the retention diagrams were drawn using interactions between PVBC-DEA with selected isomer solvents (i-butyl acetate, n-butyl acetate and t-butyl acetate) at between 85 and 110°C. The glass transition temperature value of the polymer was determined from the retention diagrams as 76°C and the obtained value, it has been understood that this value is compatible with 75.2°C found by differential scanning calorimetry. The selectivity coefficients, ∝, of the isomer solvents were determined for the PVBC-DEA in the infinite dilution, according to the results obtained, it was revealed that the polymer can separate the isomers. The polymer-solvent interaction parameters for Flory-Huggins theory, χ12∞, and the equation of state theory, χ12*,the effective exchange energy parameters, χeff, the weight fraction activity coefficient, Ω1∞, and also the partial molar heat of mixing at infinite dilution of solvent, ΔH¯1∞, the molar heat of vaporization of solvent, ΔH¯v, and the partial molar heat of sorption of solvent, ΔH¯s, were calculated between 85 and 110°C. The obtained results were discussed.