Polylactic Acid Nonwoven Fabric Surface Modified with Stereocomplex Crystals for Recyclable Use in Oil/Water Separation

Polylactic acid (PLA) is a biodegradable, environmentally friendly polymer that is gradually being used in oil/water separation. To improve its performance, coating and deposition methods have been adopted in recent years. In this paper, a superhydrophobic and superoleophilic PLA nonwoven fabric with stereocomplex (SC) crystals was prepared by a nonsolvent-induced phase separation method using only a small amount of poly(d-lactic acid) (PDLA). Scanning electron microscopy and differential scanning calorimetry characterization confirmed that SC crystals were formed on the PLA nonwoven fabric, resulting in a rough surface. The performance of the prepared fabric remained excellent after multiple uses because PDLA and poly(l-lactic acid) are connected via strong hydrogen bonding in the SC crystals. We also performed detailed theoretical analysis by using the data from atomic force microscopy, water contact angle, and flux measurements, which validated, from a theoretical perspective, that the SC crystal plays an important role in oil/water separation.