Roll-to-Roll nanoimprint lithography of polyethersulfone ultrafiltration membranes and fouling mitigation effects
September 11-16, 2016
Previous research has shown that embossing commercial polyethersulfone ultrafiltration membranes with sub-micron surface patterns increases the critical flux and reduces the rate of cake layer formation when filtering model solutions. These membranes were created using traditional nanoimprint lithography (NIL), by which a lithographically defined silicon wafer is pressed against a membrane at elevated temperatures and pressures. In order for this technological advance to be translated into commercial application, the embossing must be done using a high-throughput manufacturing method.
The focus of ongoing research has been to move the imprinting process into a roll-to-roll process. In this process, the membrane and mold are fed through a pair of rollers, and at the center nip of the rollers, the membrane is pressed into the periodic grooves of the mold. There are two ways of controlling the pressure applied by the rollers. The first is to set a distance between the rollers (roll gap), such that a percent reduction in thickness of the membrane defines pressure. The second is to have a moving roll gap where a constant force is applied to the rollers, thus a constant pressure to membrane. We have found that both methods successfully transfer patterns to the membrane. Preliminary results have shown that pattern transfer can be obtained at room temperatures, with permeance (though somewhat reduced) being retained by the membrane.
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Jacob Hutfles, Xiao Yun Lu, and John Pellegrino, "Roll-to-Roll nanoimprint lithography of polyethersulfone ultrafiltration membranes and fouling mitigation effects" in "Advanced Membrane Technology VII", Isabel C. Escobar, Professor, University of Kentucky, USA Jamie Hestekin, Associate Professor, University of Arkansas, USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/membrane_technology_vii/62