A research group has developed a smart, ion-selective porous membrane that can respond to external stimuli, potentially paving the way for new applications in molecular separation and detection applications.
Porous thin films have caught the attention of scientists because of their potential use in sensors, energy recovery, and ion / molecular separation.
The properties of the nanostructure, such as pore size, film thickness and density, affect molecular selectivity and molecular permeability. Surface properties also have a significant impact on molecular selectivity.
It is therefore important to be able to control both the 3D nanostructures and the surface properties of ultra-thin porous films.
Previous research has shed light on smart porous membranes, which are coated with molecules capable of responding to external stimuli such as light, temperature, and pH. Yet their application to porous thin films with an extremely thin film thickness of less than 10nm has proven to be extremely difficult for scientists.
“In our study, we succeeded in developing reactive porous SiO2 thin films with an extremely thin film thickness of 8 nm with a surface evenly covered in a pH sensitive silane coupling agent, ”said Yuya Ishizaki of Tohoku University Graduate School of Engineering and co-author of the ‘study. a thin film can adjust the surface charge according to the change in pH in the solution, resulting in selective permeation of ions. “
To prepare porous films with a controlled structure with precision at the nm scale, the research group focused on polymer thin films containing silsesquioxanes, which have unique cage structures.
Polymer films were made using the Langmuir-Blodgett technique, chosen because it allows molecular scale controllability of film thickness. Langmuir-Blodgett Polymer Nanosheets Also Make Porous SiO2 Thin films with nanostructures controlled by simple UV-straight irradiation under ambient conditions.
“We plan to develop highly efficient separation membranes and detection materials in the future that will take advantage of the extremely thin film thickness and controlled surface properties,” Ishizaki added.
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