Effect of Tween 80 on morphology and performance of poly(L-lactic acid) ultrafiltration membranes

Poly(L-lactic acid) (PLLA) ultrafiltration (UF) membrane was fabricated by immersion precipitation method using Tween 80 as an additive. Membrane structure was characterized by scanning electron microscopy (SEM), porosity and pore size measurement, and atomic force microscopy (AFM). Membrane performance was evaluated by pure water flux, molecular weight cut-off, and tensile test. It was found that the addition of Tween 80 into the casting solution significantly increased the permeability and molecular weight cut-off of membrane. Tensile test confirmed that the as-prepared PLLA membranes exhibited acceptable mechanical properties for ultrafiltration. Further, the role of Tween 80 in the process of membrane formation was analyzed and proposed. The addition of Tween 80 favored the formation of larger pores by interrupting the polymer chain entanglement and improving the miscibility between solvent and coagulant. (C) 2016 Wiley Periodicals, Inc.