Investigation of the effect of UV-Crosslinking on Isoporous membrane stability 

Abstract: Polymeric isoporous membranes have many interesting properties leading to various specific applications in different fields. However, such structures also have one main drawback, namely their poor solvent stability, which should be improved to extend the range of their possible applications. Therefore, this project will focus on the enhancement of solvent stability of polymeric isoporous membranes by UV cross-linking. Stable isoporous films were obtained by creating honeycomb membranes from star polystyrene (PS) and its derivatives. The star PS was synthesized by Atom Transfer Radical Polymerization (ATRP) method and was then functionalized with methacrylate groups. The isoporous films made from these materials maintained the honeycomb structures after curing by UV light and immersion in chloroform. The crosslinking of PS under UV light exposure rather than the cross-linking of the methacrylates groups was responsible for the solvent stability of these membranes. To further investigate the effect of specific end-groups on the film stability, PEG2k-G3-PCL30 linear-dendritic-linear hybrid polymers and its derivatives with allyl, acrylate, methacrylate end-groups were employed to cast films. Functionalized PEG2k-G3-PCL30 linear-dendritic-linear hybrid isoporous films were cross-linked by UV-induced thiol-ene reactions and allyl reactions. However, no significant increase in the solvent stability of these kinds of films was observed. When mixing PEG2k-G3-PCL30 linear-dendritic-linear hybrids with star PS, stable isoporous films could be obtained. The pores became smaller but the isoporous structures were still kept.