Hierarchical porous poly(l-lactic acid)/SiO2 nanoparticles fibrous membranes for oil/water separation

Abstract

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).

Hierarchically Porous, Superhydrophobic PLLA/Copper Composite Fibrous Membranes for Air Filtration

“…It is widely recognized that PLLA is a hydrophobic material. Therefore, the water contact angle of PLLA samples in this research was 144.9 ± 2.3° as expected . The deposition of copper particles onto the fibrous membrane made the surface rougher with higher contact angle .…”

“…Therefore, the water contact angle of PLLA samples in this research was 144.9 ± 2.3°as expected. 62 The deposition of copper particles onto the fibrous membrane made the surface rougher with higher contact angle. 63 Furthermore, copper particles could act as a nonwetting material, thereby increasing the hydrophobicity of the surface.…”

Electrospun Biodegradable Poly(L-lactic acid) Nanofiber Membranes as Highly Porous Oil Sorbent Nanomaterials

“…In addition, porous PLA fibers can also be prepared by some advanced electrospinning techniques such as blending spinning or coaxial spinning [ 39 , 40 ]. Moreover, several existing studies indicated the acetone post-treatment seemed to be an effective strategy for the increase of pore number and specific surface area of PLA fibers [ 17 , 41 ]. However, how to generate porous PLA nanofibers with decreased and uniform diameter and improved pore size and porosity still remains a huge challenge.…”

Hierarchical Porous PLLA@TiO2 Fibrous Membrane for Enhanced and Stable Photocatalytic Degradation Efficiency

“…However, BET results for other samples are not provided. Due to the complex pore structure of the hierarchical porous PLLA@TiO 2 membrane surface and the wide distribution of pores, with pore sizes ranging from a few nanometers to several hundred nanometers, the BET measurements do not provide accurate information on the pores of the membranes. , As the TiO 2 NPs contents increase, the porous structures of the PLLA fiber surface decrease and are replaced by numerous TiO 2 NPs. This result suggests that the addition of large amounts of TiO 2 NPs may prevent the solvent-induced crystallization of PLLA fibers into surface porous structures by the acetone solution.…”