A Study of Hierarchical Porous Poly(L-lactide)/SiO2 Nanoparticles Nanofibrous Membranes

Abstract

Poly(L-lactic acid) (PLLA) is a renewable environmentally friendly biopolymer material, which exhibits high potential in bio-applications. Combining of SiO2 nanoparticles with polymer fibres demonstrates a prospective prospect in water treatment and bone regeneration. With subsequent characterizations, structural morphology, crystallinity, mechanical, physical and chemical properties of as-prepared membranes are investigated. First, a straightforward fabrication method utilized electrospinning technology and post-process to induce the formation of porous PLLA fibres. With subsequent analysis, it showed that acetone caused PLLA to recrystallize to form a 3D interconnection porous structure. The tensile stress of these porous PLLA fibres could reach 8.07 ± 0.52 MPa, which is twice stress of the nonporous PLLA fibres. The specific surface area of porous PLLA fibres is about 10-20 times that of nonporous PLLA fibres. These advances lead to these porous substrates can be employed in many fields in the future. Second, modified SiO2 nanoparticles were successfully introduced into porous PLLA fibres via a two-step strategy. Modified nanoparticles were mixed with PLLA electrospinning solutions for pristine composite fibres fabrication. With a subsequent post process, the hydrophobic porous composite fibres were obtained and whilst the original covered nanoparticles were exposed from fibres. The strain of developed porous composite membranes could reach 80.82% and the contact angle of these fibres could reach about 152°. These advancements allow the oil flux of composite membranes could reach 5200 Lm-2h-1. Thus, these porous composite membranes have high potential in oil/water separation application. Finally, hydrophilic composite membranes were fabricated via electrospinning and dopamine surface modification. On the porous PLLA fibres, hydrophilic SiO2 nanoparticles were grafted onto the surface of fibres, forming hierarchical structure with enhanced hydrophilicity. After grafting, the water contact angle of prepared membranes could be reduced from 136.97 ± 1.50° to 96.37 ± 1.22°. In particular, the combination of dopamine grafting and 0.10 wt% SiO2 nanoparticles showed the most significant improvement. Thus, the corresponding enhanced surface roughness and hydrophilicity of the composite membranes lead to improved cell attachment and proliferation and result in better biological performance. It is suggested that these composite membranes are hopeful for the bone regeneration.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Hugh Gong (Supervisor) & Jiashen Li (Supervisor)