Laser Patterning of Porous Support Membranes to Enhance the Effective Surface Area of Thin-Film Composite-Facilitated Transport Membranes for CO2 Separation.

Although thin-film composite membranes have achieved great success in CO2 separation, further improvements in the CO2 permeance are required to reduce the size and cost of the CO2 separation process. Herein, we report the fabrication of composite membranes with high CO2 permeability using a laser-patterned porous membrane as the support membrane. High-aspect-ratio micropatterns with well-defined micropores on their surface were carved on microporous polymer supports by a direct laser writing process using a short-pulsed laser. By using a Galvano scanner and optimizing the laser conditions and target materials, in-plane micropatterns, such as microhole arrays, microline grating, microlattices, and out-of-plane hierarchical micropatterns, were created on porous membranes. An aqueous suspension of hydrogel microparticles doped with an amine-based mobile carrier was sprayed onto the patterned surface to form a defect-free thin separation layer. The surface area of the separation layer on the patterned support is up to 80% larger than that of flat pristine membranes, resulting in a 52% higher CO2 permeance (1106 GPU) with a CO2/N2 selectivity of 172. The laser-patterned porous membranes allow the development of inexpensive and high-performance functional membranes not only for CO2 separation but also for other applications, such as water treatment, cell culture, micro-TAS, and membrane reactors.

Design Rationale for CO2 Separation Membranes with Micropatterned Surface Structures.

Here, we report the design rationale of CO2 separation membranes with micropatterned surface structures. Thin film composite (TFC) membranes with micropatterned surface structures were fabricated by spray coating amine-containing hydrogel particles on the top of micropatterned porous support membranes, which were synthesized by a polymerization-induced phase separation process in a micromold (PIPsµM). The pore size of the support membranes was optimized by tuning the proportion of good and poor solvents for the polymerization process so that the microgels would be assembled as a defect-free separation layer. The relationship between the size of the micropatterned structures on the surface of the support membrane and the thickness of the separation layer was optimized to maximize the surface area of the separation layer. The rationally designed micropatterned TFC membrane showed a CO2 permeability (835.8 GPU) proportional to the increase in surface area relative to the flat membrane with a high CO2/N2 selectivity of 58.7. The rational design for micropatterned TFC membranes will enable the development of inexpensive and high-performance functional membranes not only for CO2 separation but also for other applications such as water treatment and membrane reactors.