Products Cited in Publications Worldwide Switchable gas permeability of a polypropylene-liquid crystalline composite film

Switchable gas permeability of a polypropylene-liquid crystalline composite film

Houben, Simon J. A.; Kloos, Joey; Borneman, Zandrie; Schenning, Albert P. H. J.

DOI:

Abstract

The development of functionalized polyolefins for use as stimuli-responsive commodity polymers has recently received much attention. In this work, a microporous polypropylene (PP) scaffold is used to align and fortify a smectic liquid crystalline network (LCN) which can switch its gas permeability upon pH changes. The LCN is a photopolymerized liquid crystalline mixture of a dimerized benzoic acid derivative monoacrylate and a diacrylate crosslinker. In the hydrogen-bonded state, the composite membrane shows a high-mol. order and a low permeability for He, N2, and CO2 gases. By pH switching from the hydrogen-bonded state to the salt form, the mol. order is reduced, and the gas permeability is increased by one order of magnitude. This increase is mainly attributed to a loss in order of the system, increasing the free volume, resulting in an increased diffusibility. By exposing the composite film to basic or acidic environments, reversible switching between low and high gas permeability states is observed, resp. The phys. constraints imposed by the PP scaffold strengthens the membrane while the reversible switching inside the liquid crystalline polymer is maintained. This switching of gas permeation properties is not possible with the fragile freestanding LCN films alone.

Keywords

liquid crystals ; polymer barrier coatings ; polymer gas membranes ; polyolefins ; stimuli responsive materials

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4-((6-(Acryloyloxy)hexyl)oxy)benzoic acid

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