Effects of surface modifying macromolecule (SMM) on the properties of polyethersulfone membranes

Surface modifying macromolecules (SMMs) were synthesized and blended into the casting solution of polyethersulfone (PES) membranes. The solution was cast to films on the glass plate. The cast films were placed in a temperature-controlled oven with forced air circulation to remove the solvent, before being immersed into water at 4°C for gelation. The following effects on the properties of the PES membranes were found. 1) Mechanical strength of the PES membrane was enhanced by adding SMMs. 2) According to the contact angle measurement, surface hydrophobicity of the PES membrane increased as solvent evaporation period increased. X-ray Photoelectron Spectroscopy (XPS) detected surface migration of SMMs 3) SMM blended PES membranes have potential to be used for the purpose of membrane distillation.

The following conclusions were drawn from this work: 1. The tensile strength and % elongation of the PES membrane increased when SMM was blended. 2. SMMs migrated toward membrane surface, approaching the equilibrium SMM concentration. 3. SMMs surface migration was faster for a thinner membrane. 4. Water entry pressure increased with an increase in evaporation time. Fig. 8. Water entry pressure as functions of evaporation time and casting film thickness.