Bio-inspired, biodegradable, and fluffy 3D PLA fibrous sponges with dynamic fractal nano-sweepers for on-demand oil/water separation

Frequent oil leakage results in a huge waste of fossil fuel resources and severely threatens the global water-waste-energy nexus. Membrane separation technology is a promising effective and energy-saving approach for recycling waste oil resources and oily-environment remediation. Despite many bioinspired materials with the mitigated selectivity/permeability trade-off having been developed, a significant issue has been ignored, that is, most of the membranes are non-biodegradable and could cause secondary environmental pollution. In this work, inspired by the natural 3D coral organisms with sustainable fiber tentacles; we propose a biomimetic crystal-engineering strategy of space-confined solvent-induced recrystallization to prepare a 3D biodegradable PLA fibrous sponge with coral-like nanoflower/honeycomb sweeper arrays. By virtue of the coral-like nanoporous fractal arrays with superhydrophobicity and proactive fouling resistance, the resulting PLA sponge exhibits excellent separation performance of immiscible oil–water mixtures (ultrahigh permeation flux of up to 27,908 L m -2 h −1 ) and water-in-oil emulsions (high separation efficiency of up to 99.9 %). Significantly, with the advantage of biodegradability and recyclability of PLA, we envision such environmentally friendly PLA fibrous sponges would show promising potential in the fields of environmental remediation, oil recovery, self-cleaning, etc.