Sulfonated, Disulfide-Bridged Polymer Networks for Atmospheric Water Harvesting

Access to clean water is rapidly becoming a global crisis. The atmosphere holds up to six times the volume of water as all the rivers and lakes on earth combined, thus making atmospheric water harvesting a promising solution for clean water production. Sulfonated, hypercrosslinked-style polymer networks are designed herein by Friedel-Crafts alkylation and thiol self-condensation, using disulfide bonding to convey network mobility. Varying the amount of acid polymerization catalyst generates high-capacity materials (1.39 g g^-1water sorption at 90 % relative humidity (RH) and 25°C), capable of impressive adsorption (0.26 g g^-1) at low humidities of 30%. The high adsorption capacity is predicted to be imparted by the rotational freedom of hydrophilic sulfonic acid groups, which accommodate significant water cluster formation and growth. We suggest that the polymers increase their own water harvesting capacity mechanically via conformational rearrangement, evidenced by an increased total uptake capacity of 1.60 g g^-1 at 90% RH after repeated adsorption and desorption.