Polyurethane foaming with CO2 adducts from C8 alkyl grafted polyethyleneimines: Optimization of the grafting rate and application of the blowing agents

We previously explored a series of CO₂ adducts from alkylated polyethylenimines with C₄ to C₁₆ alkyl side chains, serving as climate-friendly blowing agents for polyurethanes (PUs). Among them, the polyethylenimine with C₈ alkyl (2-ethylhexyl) side chains demonstrated the highest foaming efficiency. In this study, we further changed the grafting rate of the C₈ 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 CO₂ 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%-C₈-alkylated blowing agent demonstrated high suitability for the foaming systems from biomass-sourced polyols (like Polycin T-400). Therefore, the optimized CO₂-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.