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

Focused on the design and construction of controllable surface microtopographyand interconnected pore morphology of porous poly (L-lactic acid) membrane. A simple solvent evaporation-induced precipitation method is 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 broadened to 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 degrees 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.

Automated summary

By adjusting the PLLA concentration and/or precipitation temperature, controllable microstructures and interconnected pore morphology of porous PLLA membranes can be easily achieved. The prepared PLLA membranes exhibit high crystallinity ranging from 61.8% to 75.8% and a greatly increased maximum water contact angle of 142.3 degrees. The membranes also demonstrate enhanced mechanical damage resistance, increased porosity up to 90.8%, and higher oil-absorption capacity at 24.1 g/g, showing great potential for application as a biodegradable oil-water separation material.