Functionalized poly(arylene ether sulfone) containing hydroxyl units for the fabrication of durable, superhydrophobic oil/water separation membranes

Abstract

The stability of superhydrophobicity is crucial for the long-term application of an oil/water separation membrane in harsh environments such as high temperatures and various aggressive solvents. However, achieving such a stable superhydrophobic membrane remains a challenge. In this study, high performance fibrous oil/water separation membranes with a highly stable superhydrophobicity were fabricated by designing a functional polymer containing hydroxyl units. The reaction of hydroxy groups in poly(arylene ether sulfone) with octadecyltrichlorosilane (OTS) produces stable covalent interactions, which greatly enhance the stability of OTS on the PAES–OH (polyarylene ether sulfone containing hydroxy units) fibrous membrane fabricated by electrospinning, thus improving the stability of superhydrophobicity of the membrane. The stability of the OTS layer was characterized by FT-IR, SEM and water contact angle measurement. The results suggest that OTS is highly stable on a PAES–OH membrane, while OTS on a polyethersulfone (PES) fibrous membrane is detached from the fiber during ultrasonic cleaning. The obtained membrane is superhydrophobic, with a water contact angle (CA) as high as 159.2° and a threshold sliding angle (TSA) as low as 7.8° even after ultrasonic cleaning for 3 h. In addition, the oil/water separation experiments indicate that this membrane has an excellent performance in the separation of oil from oil/water mixtures, and oil/water emulsions: the gravity driven flux is 7260–8720 L (m² h)⁻¹ and the water rejection is over 99%. This study provides a new approach for fabricating oil/water separation membranes with highly stable superhydrophobic properties from the perspective of designing new polymers.