“Cobweb locking raindrops” inspired construction of bio-based 3D porous molecularly imprinted membrane with ultrahigh adsorption capacity and selectivity: Effectively avoiding imprinting sites embedment

Generally, 2D “thin-film” structural molecularly imprinted membranes (MIMs) prepared by the common phase inversion method suffer low adsorption capacity due to the easy embedment of imprinting sites. Herein, an alternative “delayed phase inversion” strategy was first developed to construct a natural loofah-based 3D porous MIM (LPMIM), in which the as-prepared molecularly imprinted polymers (MIPs) with artesunate (ARU) as dummy template spontaneously interacted with the polyvinylidene fluoride (PVDF) pre-treated loofah framework (LPM), and evenly anchored on loofah fiber surfaces, similar to the cobweb locking raindrops. Interestingly, the natural 3D fiber cross networks of loofah not only provided sufficient capacity and space to support MIPs without causing aggregation and maintains high flux, but also the inherent high mechanical strength of loofah fibers endowed the LPMIM with excellent stability. Under dynamic conditions the ART adsorption capacity of LPMIM could be further remarkably improved by tailoring the flow rate of 1.19 mL·cm−2·min−1, up to 334.70 mg/g. As a result, effective enhancement in the artemisinin (ART) adsorption capacity were achieved for the LPMIM, which was about 2.25 times higher than that of the common blend MIM prepared by common phase inversion method (148.30 mg/g). Moreover, the LPMIM possessed high ART selectivity towards its analogue, artemether (ARE), giving an ART/ARE ratio of 2.7. Furthermore, the LPMIM displayed excellent recycling performance. By altering the template of MIPs, the corresponding LPMIM can be expanded to highly selective separation of other substrates along with large absorption capacity. This work highlights a universal strategy to construct novel MIMs with high absorption capacity and selectivity using bio-based fiber cross frameworks.