A two-step strategy has been developed to introduce silica nanoparticles into highly porous poly(l-lactic acid) (PLLA) nanofibers. Silica nanoparticles (SiNPs) were firstly synthesized and then modified to be hydrophobic. After PLLA/SiNPs composite fibrous membranes were electrospun and collected, they were re-crystallized by acetone at room temperature for a few minutes. With the re-arrangement of PLLA chains, the nano-/micro-electrospun fibres were transformed from non-porous ones to be porous ones with high surface area. Consequently, SiNPs that were completely covered by PLLA before acetone treatment showed up at the fibre surface. Higher PLLA crystallization also enhanced the Young’s modulus and tensile strength (420 and 8.47 MPa) of the composite membrane. However, incorporation of SiNPs into porous PLLA membranes reduced their modulus and tensile strength (280.66 and 5.92 MPa), but an increase in strain to fracture (80.82%) was observed. Scanning electron microscopy (SEM), focused ion beam SEM, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction were applied to confirm the presence of SiNP in PLLA fibres. The presence of SiNPs inside and outside fibres enhances the hydrophobicity of PLLA/SiNPs nano-fibrous membrane as the water contact angle is greater than 150°. The oil absorption of these porous composite membranes was also tested using four different oils, which can reach the highest absorption capacity when the weight ratio of PLLA and SiNPs is 1:1. The flux of prepared membranes was investigated, and results indicated that SiNPs-loaded membrane effectively enhanced the flux (5200 Lm−2 h−1).

中文翻译：

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用于油/水分离的分层多孔聚（l-乳酸）/SiO2纳米颗粒纤维膜

已开发出两步策略将二氧化硅纳米粒子引入高度多孔的聚（l-乳酸）（PLLA）纳米纤维中。首先合成二氧化硅纳米粒子（SiNPs），然后将其改性为疏水性的。PLLA/SiNPs复合纤维膜经静电纺丝和收集后，在室温下用丙酮重结晶几分钟。随着PLLA链的重新排列，纳米/微电纺纤维从无孔纤维转变为具有高表面积的多孔纤维。因此，在丙酮处理之前被 PLLA 完全覆盖的 SiNP 出现在纤维表面。较高的 PLLA 结晶也提高了复合膜的杨氏模量和拉伸强度（420 和 8.47 MPa）。然而，将 SiNPs 掺入多孔 PLLA 膜会降低其模量和拉伸强度（280.66 和 5.92 MPa），但观察到断裂应变增加（80.82%）。应用扫描电子显微镜 (SEM)、聚焦离子束 SEM、透射电子显微镜、傅里叶变换红外光谱和 X 射线衍射来确认 PLLA 纤维中 SiNP 的存在。当水接触角大于150°时，纤维内外SiNPs的存在增强了PLLA/SiNPs纳米纤维膜的疏水性。还使用四种不同的油对这些多孔复合膜的吸油性进行了测试，当 PLLA 和 SiNPs 的重量比为 1:1 时，可以达到最高的吸油量。研究了制备的膜的通量，