Highly miscible bio-based poly(lactic acid)/acetylated cellulose ether ultrafiltration membranes with improved water permeances

Abstract

Biopolymer-based membranes are eco-friendly alternatives to petroleum-based membranes. However, biopolymers often require harsh membrane fabrication conditions due to their low solubilities, which are incompatible with general non-solvent-induced phase separation (NIPS). Thus, establishing mild blending conditions for NIPS membrane production is needed. This study developed ultrafiltration membranes by blending poly (lactic acid) (PLA) and acetylated cellulose ether (ACE), both of which are derived from renewable resources, using NIPS under mild conditions. We investigated the effects of PLA proportion on the structural, chemical, and thermal properties of the blend membranes and assessed polymer miscibility using theoretical models. Results indicated excellent miscibility with a single glass transition temperature. The 1:1 PL A/ACE membrane demonstrated the lowest water contact angle of 45 degrees, 35 % lower than that of the pure PLA membrane. Additionally, its pure water permeance was 179.4 LMH/bar, significantly higher than 103.4 LMH/bar of the pure PLA membrane. Flux recovery ratio at pH = 4 was 69.5 for the blend membrane as compared to 70.6 for the PLA membrane. At pH = 7, all membranes could be fully recovered via physical washing, even those fouled with bovine serum albumin. This study successfully fabricates PLA/ACE-based membranes with outstanding properties under mild conditions.