Controllable surficial and internal hierarchical structures of porous poly (L-lactic acid) membranes for hydrophobicity and potential application in oil-water separation

Abstract

Focused on the design and construction of controllable surface microtopographyand interconnected pore morphologyof porous poly (L-lactic acid) membrane. Asimple solvent evaporation-induced precipitation methodis proposed to regulate microstructures by one-step method without any additive. Controllable microstructures (fibrous networks, interconnected pores, and crystallized PLLA protrusions) and interconnected pore morphology were facilely achieved by adjusting the PLLA concentration and/or precipitation temperature. In view of the shortcomings of previous foam preparation, the contact area between solvent and non-solvent was broadenedto realize the improvement of porosity and the construction of surface micro-nano structure. The results show that the crystallinity of prepared PLLA membranes is kept in a high range between 61.8% and 75.8% and the maximum watercontact angle (WCA) is largely increased to 142.3°. Surprisingly, surface wettability of PLLA membranes possess the wonderful mechanical damage resistance, and the porosity and oil-absorption capacity are increased to 90.8% and 24.1 g/grespectively. Predictably, the porous PLLA membrane has great application potential as a biodegradable oil-water separation material.