Structural conversion of PLLA/ZnO composites facilitated by interfacial crystallization to potential application in oil-water separation

Abstract

Focus on the potential application in oil-water separation for porous and biodegradable Poly(L-latic acid) (PLLA) amenable to economically viable water treatment, we designate the controllable pores, fibrillary network and protrusion structure by crystallization induced phase separation in poly(L-latic acid)/Zinc oxid (PLLA/ZnO) materials, ready for their potential application in oil-water separation. It’s worth noting that the interface effect between PLLA and ZnO is strengthened by silane coupling agent KH570. The crystallinity of the PLLA/ZnO@KH570 materials are correspondingly increased from 36.9% to 41.1% as the slightly increasing content of ZnO@KH570 from 1% to 7%, indicating that ZnO@KH570 nanoparticles can act as heterogeneous nucleating agent to promote crystallization of PLLA, which facilitate the conversion of PLLA solution from liquid-liquid phase separation mechanism to solid-liquid phase separation mechanism, resulting in the formation of microstructures. Very interestingly, the porosity of PLLA/ZnO@KH570 composite is highest up to 94.1% compared to its value of 87.8% for pure PLLA. Due to the multiple structures, the water contact angle of composite is significantly improved to 146°, allowing the oil/water mixture solution to be effectively separated. In brief, we have successfully manufactured hydrophobic PLLA/ZnO@KH570 composite with the multi-scale microstructure which may be potentially applied in oil-water separation.