Climate‐friendly polyurethane blowing agent based on a carbon dioxide adduct from palmitic acid grafted polyethyleneimine

To explore a new blowing agent for polyurethanes (PUs), palmitic acid was grafted onto a branched polyethyleneimine (bPEI; weight‐average molecular weight = 25,000 Da) via N,N ′‐carbonyldiimidazole condensation to form a hydrophobically modified bPEI [palmitic acid grafted branched polyethyleneimine (C 16 –bPEI)] with a grafting rate of 12%. A CO 2 adduct of C 16 –bPEI, which trapped 16.8% CO 2 in it, was synthesized from C 16 –bPEI. The long alkyl chain grafting improved the dispersibility of the CO 2 adduct in the PU raw materials and favored a homogeneous release of CO 2 to blow PUs during the exothermic foaming process. The preliminary results show that the foams possessed a density of 72.0 kg/m 3 and a compressive strength of 246 kPa; this matched the required values of foams for the thermal insulation of underground steel pipes. This new blowing agent emitted nothing but CO 2 to the atmosphere, so it will not promote ozone depletion and will avoid global warming problems that are associated with traditional blowing agents such as chlorofluorocarbons and hydrochloroflourocarbons. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43874.