Preparation of polypropylene based hyperbranched absorbent fibers and the study of their adsorption of CO2

Ring-opening copolymerization of aziridine in situ into substrates to introduce polyethyleneimine (PEI) not only required strict experimental conditions but employed the highly toxic monomer aziridine. In this paper, an effective and safe new procedure is developed for hyperbranched structure synthesis by stepwise growth using N-(2-chloroethyl)-benzaldimine as a monomer. Hyperbranched solid amine fibers for CO2 capture were prepared through co-irradiation grafting copolymerization of polypropylene fibers with glycidyl methacrylate, followed by amination with ethylenediamine, Hoffman alkylation with N-(2-chloroethyl)-benzaldimine and then hydrolysis to remove benzaldehyde groups. It was shown that the adsorption performance of the hyperbranched solid amine fibers G2.0 and G3.0 has been greatly improved compared with first generation G1.0 fibers, and the adsorption capacities of G2.0 and G3.0 were 5.35 mmol g−1 and 5.53 mmol g−1 at 30 °C, respectively. The amine utilization of G2.0 fibers could reach 84.1%. These results demonstrate that the branched structure can promote the adsorption capacity and efficiency greatly due to its low mass transfer resistance of CO2, which is more favorable than a linear amination reagent.