Porous Polymer Membranes by Hard Templating – A Review

Abstract

Membranes are designed to bridge a precise separation process at the nanoscale with industrial applications running at cubic meters per hour. This review outlines materials applied in membrane production with a particular focus on polymers. Membrane performance and created value are directly linked to controlled pore formation. Their economic relevance has created a number of large companies and associated academic research at top institutions. The authors review, therefore, starts from well-established techniques applied in products and then moves on to evolving concepts from academia. Pore formation through hard templating is a versatile field for separation processes. A more detailed view is given on the two known concepts for nanopore formation, namely colloidal templates and random hard salt templating. A comparison between these two concepts underlines their relevance to combine a process specific separation with large scale manufacturing requirements (i.e., upscale possibility, flexible process control and environmental impact).

Progress Report on Phase Separation in Polymer Solutions

“…Commercially relevant methods [3] include tearing, foaming, self-assembling templates, track edge, weaving, polymer mixing, and block copolymers, covalent organic frameworks, and phase separation where the last one is the focus of this review. Commercially relevant methods [3] include tearing, foaming, self-assembling templates, track edge, weaving, polymer mixing, and block copolymers, covalent organic frameworks, and phase separation where the last one is the focus of this review.…”

“…Commercially relevant methods [3] include tearing, foaming, self-assembling templates, track edge, weaving, polymer mixing, and block copolymers, covalent organic frameworks, and phase separation where the last one is the focus of this review. [3] While in earlier days of engineering materials, the avoidance of porosities was the main objective, [6] in PPM it is explicitly utilized to provoke the aforementioned beneficial capabilities of the polymer materials and to facilitate versatile and momentous applications. Herein, the poly mer grows around a template matrix which could be a solid (hard templating), [3] an emulsion (emulsion templating), [4] or a dispersed gaseous phase (foam templating), [5] to name a few.…”

“…Since the way of introducing pores into polymers has been investigated for many years now, a large number of formation processes thrive on both industrial and academic fields. Commercially relevant methods [3] include tearing, foaming, self-assembling templates, track edge, weaving, polymer mixing, and block copolymers, covalent organic frameworks, and phase separation where the last one is the focus of this review. In academia, another method is proposed based on the pore formation through templating.…”

“…In academia, another method is proposed based on the pore formation through templating. Herein, the poly mer grows around a template matrix which could be a solid (hard templating), [3] an emulsion (emulsion templating), [4] or a dispersed gaseous phase (foam templating), [5] to name a few. As a result, the intrinsic properties of the template are inherited to the PPM.…”

Single Solvent‐Based Film Casting Method for the Production of Porous Polymer Films

“…[23] Most of these production processes have lengthy and/or complicated manufacturing processes and can use several types of sacrificial materials and/ or solvents. [24] For example, the breath figure method involves generating condensed water droplets on the surface of evaporating polymer solution, which requires tight control over the humidity environment of the film drying site. [20,25,26] A foaming-polymerization process has also been investigated to prepare a polyaniline (PANI)/polyvinyl alcohol (PVA) porous foams, [27] where a specific amount of aniline and PVA were dissolved in water followed by incorporation of air bubbles utilizing a mechanical stirrer.…”