Synthesis of Cyclodextrin-Containing Polyurethanes for Pervaporation Separation of Phenol/Water Mixtures

The new kind of polyurethanes (PU) were synthesized based on both of diamine and β-cyclodextrins (β-CDs) as chain extenders and hydroxyl-terminated polybutadiene (HTPB) as soft segment via a two-step method. First, HTPB reacted with 2, 4-toluene diisocyanate (TDI) with the molar ratio of 1/2, and NCO-terminated prepolyurethane was obtained. Then chain extenders such as 4, 4’-diaminodiphenyl methane (MDA) or MDA+β-CDs were added to the prepolymer solution. Finally, the membranes of PU were prepared by solution casting. The structures and properties of PU membranes thus obtained were characterized by means of FT-IR, DSC and TGA. Furthermore, the pervaporation (PV) performances were investigated for separating aqueous solution with 0.5wt% phenol at different temperatures. The results showed that the total fluxes of the PU membranes increased with the increased feed temperature, while those separation factors decreased. Comparing to the PU membranes without cyclodextrin, those containing β-CD obtained better separation performances.