Polyurethane foams are typically obtained by reacting a polyisocyanate with a polyol and the foamed structure derives from a blowing reaction concurrent to the polymerization reaction. The blowing stage makes use of chemical and physical blowing agents, among which ozone-depleting or flammable gases are being substituted with eco-friendly and safe ones, such as CO2. To allow a more educated use of CO2 as a physical blowing agent in polyurethane foams, we herein investigate the CO2 sorption in polymeric methylene diphenyl diisocyanate (PMDI), by using a fully experimental, coupled gravimetry-Axisymmetric Drop Shape Analysis. Solubility, mutual diffusivity, specific volume and interfacial tension of PMDI/CO2 solutions in contact with CO2 have been measured at 35 deg C and at CO2 pressures up to 6500 kPa. Effects of CO2 on PMDI were also evaluated by using Gel Permeation Chromatography and Fourier Transform Infrared spectroscopy. (C) 2017 Elsevier B.V. All rights reserved.