Polyurethane foaming with CO 2 adducts from C 8 alkyl grafted polyethyleneimines: Optimization of the grafting rate and application of the blowing agents

We previously explored a series of CO 2 adducts from alkylated polyethylenimines with C 4 to C 16 alkyl side chains, serving as climate‐friendly blowing agents for polyurethanes (PUs). Among them, the polyethylenimine with C 8 alkyl (2‐ethylhexyl) side chains demonstrated the highest foaming efficiency. In this study, we further changed the grafting rate of the C 8 alkyl, from 7 to 16%, and investigated the effects of the resulting blowing agents on the foaming process. For both foaming systems containing a castor oil‐derived polyol (Polycin T‐400) or a poly(propylene glycol) polyol (Polyether 4110), the CO 2 adducts with a grafting rate of 13% displayed the best foaming performance in terms of high dispersibility in the foaming systems, homogenous cellular morphology, and good mechanical properties. Moreover, the 13%‐C 8 ‐alkylated blowing agent demonstrated high suitability for the foaming systems from biomass‐sourced polyols (like Polycin T‐400). Therefore, the optimized CO 2 ‐adduct blowing agent could replace the currently used climate‐changing hydrochlorofluorocarbons and hydrofluorocarbons, as well as might contribute to the development of future renewable PU foams. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48752.