Stereocomplexed polylactic acid porous fibres for high-temperature filtration

• SC-PLA has been proven to remain stable in 150 °C high-temperature filtration. • A strategy was proposed by manipulating the molecular weight of PLA to form porous fibres. • The porous structure improved the PM 0.3 filtration efficiency of fibrous membranes to over 97%. • The toughness of porous fibrous membranes was increased by 79%. The growing demand for sustainable air filtration media has sparked interest in replacing traditional non-biodegradable filters with biodegradable materials. In this paper, a strategy was developed to regulate the fibre morphology of poly(L-lactic acid) (PLLA)/ poly(D-lactic acid) (PDLA) electrospun membranes by manipulating the molecular weights of the fibres. The strategy involved plasticisation of short PDLA chains and selective solvent-polymer interactions, which induced swelling and recrystallisation of the polymer chains to introduce a porous structure into the fibres and increase the tensile toughness of the fibrous membranes by 79 %. The porous fibres enlarged the specific surface area of the membranes and increased the PM 0.3 (particulate matter with a diameter of less than 0.3 μm) removal with a filtration efficiency (η) from around 86 % to over 97 %. In addition, the exclusive stereocomplex-crystallites in the porous fibre membranes enabled the fibres to maintain high filtration efficiencies during continuous filtration at a relatively high temperature of 150 °C. Enhanced toughness, excellent fine particle capture, and outstanding thermal stability make porous PLLA/PDLA fibrous membranes a biodegradable alternative to currently high temperature air filtration materials.