Hyperbranched polyglycerols containing amine groups — Synthesis, characterization and carbon dioxide capture

Abstract

Abstract In this article we report an easy synthetic way towards hyperbranched polyglycerols containing primary amine groups (A-HBPGs). A-HBPGs were synthesized in a two-step procedure including an anionic ring opening copolymerization of the phthalimide-epoxy monomer with glycidol followed by hydrazinolysis of phthalimide groups. Polymeric products of both synthetic steps were characterized using NMR, MALDI-TOF, FTIR, viscosimetry and elemental analysis techniques. The maximum amount of the amine containing units in the products was estimated to be 31 mol%. Introduction of higher amounts of these units was limited by the reactivity (sterical) and viscosity reasons. A-HBPGs showed to be effective in CO2 capture from the ambient air. Adsorbents consisting of A-HBPGs and fumed silica in the 1 to 1 wt ratio were capable of adsorbing up to 85.6 mg of CO2, representing 0.82 mmol CO2 per gram or 36.3 mg CO2 per gram of adsorbent. The measurements confirmed that the amount of adsorbed carbon dioxide was proportional to the number of amine sites in a polymer. The obtained CO2 adsorbents could be regenerated upon by heating. Desorption took place above 80 °C, but the optimum temperature seemed to be at least 100 °C. The effect of easier CO2 desorption in presence of HBPG structures reported in the literature in case of our materials has not been confirmed.