A specific heating pretreatment for increasing the stability of organic solvent-free polymeric membrane

The development of sustainable membrane fabrication routes remains a major challenge, as conventional polymeric membranes rely heavily on fossil-based polymers and hazardous aprotic solvents. In this work, we propose a fully solvent-free and bio-sourced approach for producing porous membranes using hydroxypropyl cellulose (HPC) and water as the only solvent. Membrane formation was achieved through an LCST-TIPS process combined with chemical crosslinking via glutaraldehyde. A detailed rheological study revealed that the crosslinking dynamics strongly depend on the evaporation of volatile components, which controls the proximity of polymer chains and thus the onset of effective crosslinking. While HPC membranes exhibited low and unstable permeabilities at room temperature due to the hydrophilic nature of the polymer, we demonstrated that a thermal conditioning step at 60 °C—where water becomes a poor solvent for HPC—substantially improves membrane performance. This pretreatment resulted in fully stabilized structures with pure-water exceeding 150 L·h −1 ·m −2 at 3.5 bar, and up to 350 L·h −1 ·m −2 during hot-water filtration (60 °C). The flux–pressure relationship became fully linear and reproducible after conditioning, confirming effective pore opening and structural stabilization. These results highlight the combined benefits of a bio-sourced polymer, water-only processing, and an energy-efficient thermal pretreatment, offering a highly promising route toward truly sustainable membrane manufacturing. • Bio-sourced, non-toxic, and energy-efficient route toward sustainable membrane manufacturing. • Fully solvent-free membrane fabrication using HPC and water as the sole solvent. • Thermal conditioning at 60 °C dramatically improves membrane stability and pore opening. • Membranes remain fully operational at elevated temperature, reaching 350 L·h −1 ·m −2 at 60 °C.