PEO-PU block copolymer membrane for air dehumidification

Abstract

Membrane separation was an efficient process for air dehumidification. In this study, an environmentally friendly and low-cost polyethylene oxide (PEO)-polyurethane (PU) block copolymer (Permax232) membrane was prepared successfully using water as solvent. An aqueous polycarbondiimide (PCD) crosslinking agent was added into the membrane to improve its water stability property. The physicochemical properties and the crosslinking mechanism of the membrane were investigated using various analytical methods. Compared with the Permax232 membrane, the cross-linked Permax232 membrane exhibited improved water stability and mechanical properties. The surface roughness of the cross-linked membrane increased, and the intensity of the crystalline peak decreased. The crosslink density increased with the PCD content based on the water swelling method. The modified Flory-Huggins model showed excellent agreement between the crosslink density and water vapor sorption. When the appropriate amount of PCD was added, the Permax232 membrane exhibited a high water vapor permeability of 1.45 × 105 Barrer and a water vapor/N2 selectivity of 8.2 × 104. In addition, the water vapor permeability of the cross-linked Permax232 membrane did not change significantly with increasing temperature at the same humidity.