Swelling properties and kinetics of CaCl2/polyacrylamide hygroscopic hybrid hydrogels

The novel hygroscopic hybrid hydrogels were prepared from polyacrylamide and calcium chloride. The hygroscopic swelling properties and kinetics of CaCl2/polyacrylamide hybrid gels were investigated. To optimize the experimental condition, the influence factors such as dissolution temperature of CaCl2, CaCl2 mass, and hygroscopic temperature relative to the hygroscopic swelling degree of hybrid desiccants were studied systematically. The research results revealed that, under the optimal experimental condition (dissolution temperature of CaCl2, 50 °C; CaCl2 mass, 80%; environment temperature, 30 °C), the hybrid gels displayed the highest hygroscopic swelling degree resulting from high hygroscopic ability of calcium chloride and good water-binding of polyacrylamide. Under the optimized experimental condition, the hygroscopic swelling degree of the hybrid gels increased with the increment of relative humidity. Furthermore, the hygroscopic swelling processes of hybrid gels followed the Schott second order dynamic equation, and the hygroscopic swelling rate decreased with the increment of relative humidity.

Research highlights▶ The novel hygroscopic hybrid hydrogels were prepared from polyacrylamide and calcium chloride. ▶ The hybrid gels have fairly high hygroscopic ability due to consisting of 80% CaCl2 and good water-binding because of polyacrylamide. ▶ Investigate the effect of dissolution temperature of CaCl2, environment temperature on the hygroscopic swelling degree. ▶ Discuss the hygroscopic swelling processes at different relative humidities by kinetics, and the swelling processes follow the Schott second order dynamic equation.