Ultrahigh-pressure and -temperature tolerant reverse osmosis membrane

Conventional thin-film composite (TFC) reverse osmosis (RO) membranes densify under applied hydraulic pressure, and this compaction of the mesoporous support layer reduces water permeability by as much as 50 percent, sharply limiting operation at the elevated pressures required for high-salinity brine concentration. Our work addressed this barrier by replacing the compactible, phase-inverted support with a fully thermoset architecture. We crosslinked a phase-inverted porous polyimide support membrane and then formed the polyamide selective layer by interfacial polymerization, producing a thin-film crosslinked (TFX) composite that resists physical compaction at ultrahigh pressures up to 200 bar. Because RO membranes compact across virtually the entire operating range, this compaction resistance carries broad implications for membrane technology , and it directly enables ultrahigh-pressure RO (UHPRO) as a low-energy route toward minimum and zero liquid discharge (MLD and ZLD) in inland desalination and brine valorization.

We extended the same thermoset design principle to thermal resilience, a second mode of irreversible failure that has historically excluded polyamide membranes from hot process streams. Conventional TFC membranes lose performance permanently at high temperatures, restricting their use in oil and gas, pharmaceuticals, electronics, power generation, food production, and hybrid desalination plants . Combining controlled experiments, molecular dynamics (MD) simulations, and micromechanical modeling, we showed that exposure above 60 degrees Celsius dropped TFC salt rejection from roughly 99 percent to below 90 percent, accompanied by irreversible structural damage in the polysulfone support. The thermally resilient TFX composite suppressed this damage, demonstrating that a crosslinked, fully thermoset support stabilizes the selective layer against both mechanical and thermal degradation and unlocks high-temperature RO desalination.