Novel Strategy for Fabricating Multilayer Porous Membranes with Varying Porosity.

Takafumi Aizawa

doi:10.1021/acsomega.0c02906

Abstract

CO2-assisted polymer compression (CAPC) is a method for fabricating porous polymer materials in which the polymer is plasticized with CO2 and then pressed. In this work, a two-step molding method is adapted, and a porous membrane with multiple layers of varying porosity is fabricated by laminating sheets of a single starting material. A model is constructed in which the expansion owing to CO2 and compression reflected by the longitudinal elastic modulus are considered. The model is constructed based on a two-layer experiment and extended to three layers. From the model simulation, the conditions for fabricating a multilayer porous polymer membrane with three layers of varying porosity (0.6, 0.5, and 0.4) and identical thickness (0.6 mm) are calculated. Finally, a porous membrane with varying porosity is fabricated based on the simulated design.

Highlights

Polymers are indispensable materials in daily life because of their lightweight and durable nature.[1]
A nonwoven fabric composed of poly(ethylene terephthalate) was used as a raw material sheet, and a three-layer porous membrane was established as a target, in which the layers obtained by stacking 10, 12, and 15 sheets have a constant
To design the desired multilayered porous membrane, a compression-after-expansion model was constructed in which compression was performed after an initial expansion by CO2, while considering the longitudinal elastic modulus

Summary

Introduction

Polymers are indispensable materials in daily life because of their lightweight and durable nature.[1] Among polymer materials, porous materials have numerous applications, such as filters, catalysts, bioreactors, and thermal insulators.[2] For example, porous fibrous materials are used for face masks,3 2.5 μm particulate matter filters,[4] water filters,[5] and filters for oil-inwater filtration.[6] In particular, nonwoven fabrics are often used in filters owing to their high productivity and low price.[7] These materials can be functional; for example, porous membranes have been used as battery separators.[8] In the study of porous materials, obtaining a high-functionality material via precise manufacturing is the major theme

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