Photo-oxidative enhancement of polymeric molecular sieve membranes

Abstract

High-performance membranes are attractive for molecular-level separations in industrialscale chemical, energy and environmental processes. The next-generation membranes for these processes are based on molecular sieving materials to simultaneously achieve high throughput and selectivity. Membranes made from polymeric molecular sieves such as polymers of intrinsic microporosity (pore sizeo2 nm) are especially interesting in being solution processable and highly permeable but currently have modest selectivity. Here we report photo-oxidative surface modification of membranes made of a polymer of intrinsic microporosity. The ultraviolet light field, localized to a near-surface domain, induces reactive ozone that collapses the microporous polymer framework. The rapid, near-surface densification results in asymmetric membranes with a superior selectivity in gas separation while maintaining an apparent permeability that is two orders of magnitude greater than commercially available polymeric membranes. The oxidative chain scission induced by ultraviolet irradiation also indicates the potential application of the polymer in photolithography technology.

Influence of the Preparation Method and Photo-Oxidation Treatment on the Thermal and Gas Transport Properties of Dense Films Based on a Poly(ether-block-amide) Copolymer

“…Furthermore, in the case of membrane technology, the photo-oxidation process can be used as a valuable strategy to tune the separation performance. As far as this point is concerned, the understanding of the photo-oxidation and stability of polymeric membranes could be a crucial point to address towards their application for gas separation, catalysis, or sensors [11]. …”

Using intermolecular interactions to crosslink PIM-1 and modify its gas sorption properties

“…4,7-17 PIM-1 is interesting for applications in gas separation membranes due to its high permeability and moderate selectivity. 16 It has been proposed that crosslinking PIM-1 may have the effect of reducing the pore size of the material thus improving its selectivity. These modication approaches generally fall into two categories: modication of the polymer backbone, or crosslinking PIM-1 to form a network.…”

Controlled thermal oxidative crosslinking of polymers of intrinsic microporosity towards tunable molecular sieve membranes

“…Recently, we reported the photooxidative degradation of PIM-1 polymer on exposure to ultraviolet light irradiation in the presence of oxygen, which induces oxidative chain scission and local densification at the surface 35 . Similarly, thermo-oxidative degradation or crosslinking could occur for PIM-1 polymer when polymers are heated in the presence of oxygen.…”