Preparation of self-crystal electret poly(lactic acid) oriented nanofibers for efficiency filtration of particulate matters

In recent years, in order to effectively reduce the danger to people's life and health caused by particulate matters (PMs) generated during industrialization, traditional non-degradable filter materials have been widely used, resulting in a serious environmental burden. Therefore, the stereocomplex crystals (SCs) were generated between enantiomeric poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) with high electroactivity were constructed from the PLLA and PDLA blends by high-temperature crystallization. The SCs were used as electret dispersed in poly(lactic acid) (PLA) solution, and under the effect of strong unidirectional mechanical polarization and high-voltage E-field polarization to prepare self-crystal electret oriented nanofibrous membranes. By varying the addition amount of SC and the unidirectional mechanical drawing to modulate the morphology of PLA nanofibers, induce the alignment of C=O dipoles, promote the generation of electroactive β-phase, and increase the interfacial polarization, the surface potential and dielectric properties of the fabricated self-crystal electret PLA oriented nanofibers were greatly improved. In addition, the self-crystal electret PLA oriented nanofibrous membranes exhibited excellent particle removal performance under strong interfacial polarization. Even at an air flow rate of 85 L/min, the self-crystal electret nanofibrous membrane reached a filtration efficiency of 97.83% for PM_0.3, while the air resistance was controlled at 293 Pa, which was superior to that of the pure PLA membrane (96.48%, 411 Pa). The proposed strategy of increasing the polarization and electroactivity of PLA nanofibers by combining self-crystal electret and oriented strategy shows excellent filtration performance, which provides an important reference for effectively solving the bottleneck of the application of traditional PLA nanofibers in the field of air filtration.