Ultrafine particulate aerosols less than 100 nm diffuse randomly in the air and are hazardous to the environment and human health. However, no technical standards or commercial products are available for filtering particle sizes under 100 nm yet. Here, we report the development of a porous poly­(l-lactic acid) (PLLA) nanofibrous membrane filter with an ultra-high specific surface area via electrospinning and a post-treatment process. After PLLA fibres were electrospun and collected, they were treated by acetone to generate a blossoming porous structure throughout each individual fibre. Characterizations of morphology, crystallinity, and mechanical and thermal properties demonstrated that the porous structure can be attributed to the nonsolvent-induced spinodal phase separation during electrospinning and solvent-induced recrystallization during post treatment. The blossoming porous structure with high specific surface area contributed to excellent filtration efficiency (99.99%) for sodium chloride (NaCl) ultrafine aerosol particles (30–100 nm) with a low pressure drop (110–230 Pa). Notably, under 7.8 cm/s air flow rate, the membrane samples performed better for filtering smaller-sized aerosol particles than the larger ones when evaluated by the quality factor (0.07). Finally, this finding demonstrates that the electrospun membrane with a hierarchical pore structure and high specific surface area hold great potential in applications as air-filtering materials.

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Porous poly(L-lactic acid) (PLLA) nanofibrous membrane with the high surface area was developed by electrospinning and post acetone treatment and used as a substrate for deposition of chitosan. Chitosan was coated onto porous nanofibrous membrane via direct immersion coating method. The porous PLLA/chitosan structure provided chitosan a high surface framework to fully and effectively adsorb heavy metal ions from water and showed higher and faster ion adsorption. The composite membrane was used to eliminate copper ions from aqueous solutions. Chitosan acts as an adsorbent due to the presence of aminic and hydroxide groups which are operating sites for the capture of copper ions. The maximum adsorption capacity of copper ions reached 111.66±3.22 mg/g at pH (7), interaction time (10 min) and temperature (25 °C). The adsorption kinetics of copper ions was established and was well agreed with the second-order model and Langmuir isotherm. Finally, the thermodynamic parameters were studied.

Electrospinning has been widely used to fabricate polymer fibrous scaffolds for bone tissue engineering because of their highly porous structures. In order to improve the biocompatibility of polymer scaffolds, some nano particles have been introduced into electrospun fibres. For example, silica nanoparticles (SiNPs), with high surface area and good biocompatibility, have been used for bone tissue engineering for better bone cell attachment. In this work, porous poly(L-lactic acid) (PLLA) fibrous membrane with high surface area was fabricated by electrospinning and posttreatment process. The membrane can serve as substrates of SiNPs for bone tissue engineering. Dopamine (DOP) was applied to modify the surface of PLLA fibres, which improved the coating strength of SiNPs on PLLA fibres. SiNP coating significantly improved the mechanical properties Manuscript File Click here to view linked References 2 and hydrophilicity of PLLA/DOP/SiNP composite membranes. As a result of SiNPs coating, PLLA/DOP/SiNP membrane exhibited better cellular biocompatibility, more cell attachment and proliferation. These results demonstrate that porous PLLA/DOP/SiNP composite membrane with high surface area has high potential for periosteum in the field of bone regeneration applications.