Roll-to-roll nanoimprint lithography of ultrafiltration membrane

Nanoimprinting of a commercial, as supplied, polyethersulfone ultrafiltration membrane has been carried out for the first time using a roll-to-roll (R2R) process. To support this processing approach, we also developed a reusable flexible polyetherimide mold. We were able to pattern membrane at room temperature (similar to 21 degrees C) due to the high pressures (22 MPa) applied during the low contact times (<2 s) inherent to R2R imprinting. N-2 permeance (L m(-2) h(-1) bar(-1)) testing was used as an indicator to verify retention of membrane porosity and to guide selection of imprinting parameters during initial screening studies. Further measurements showed the N2 and (scaled) deionized water permeances to have a 0.97 correlation coefficient. We scaled up the size of patterned membranes to as large as 226 cm(2) area, thereby demonstrating the plausibility of continuously patterning commercial ultrafiltration membranes. We also investigated pattern stability versus aqueous heat treatment and found that time, temperature, and imparted strain (during patterning) may all influence stability, but no evidence of pattern loss was observed in electron micrographs after our filtration experiments. (C) 2017 Wiley Periodicals, Inc.