Limestone nanoparticles as nanopore templates in polymer membranes: narrow pore size distribution and use as self-wetting dialysis membranes

Limestone nanoparticles can be used as nanopore templates to prepare porous polymeric films. Their application as membranes is so far strongly limited by the fact that these films are highly hydrophobic. In this study, a simple method is reported to directly produce self-wetting membranes by the template removal method. Triethyl citrate modified polyethersulfone and cellulose acetate membranes were produced using dissolvable limestone nanoparticles as pore templates. The nanoporous polymer films were used as dialysis membranes and characterized by means of buffer exchange rate, molecular weight cut-off, protein adsorption, pore size distribution and water contact angle. The herein prepared membranes were further benchmarked against commercially available dialysis membranes with comparable average pore size. They showed narrow pore size distributions, fast dialysis rates at low protein adsorption and molecular weight cut-off of around 12 kDa. Interestingly, the triethyl citrate modified polyethersulfone membranes displayed only moderate change in pore size distribution as a result of the plasticizer additive compared to pure polyethersulfone membranes. This is a matter of substantial interest considering the fact that additive modifications of membranes produced by the predominant phase inversion process typically show alterations in morphology that lead to undesired changes in membrane performance. Furthermore, dextran recovery analysis proved to meet the specific requirements for dialysis membrane characterization and benchmarking.