Effect of UV irradiation and physical aging on O2 and N2 transport properties of thin glassy poly(arylene ether ketone) copolymer films based on tetramethyl bisphenol A and 4,4′-difluorobenzophenone

Abstract

Modification of membranes to improve gas separation properties has been of considerable interest. Crosslinking is one route to modify membranes, but such studies need to be performed on thin membranes to quantify the impact of such modifications at thicknesses relevant to industrial membranes. In this study, the influences of UV irradiation and physical aging on O 2 and N 2 gas permeation properties of thin (~ 150 nm) glassy, amorphous poly(arylene ether ketone) (PAEK) copolymer films at 35 o C and 2 atm were investigated. Thin PAEK copolymer films, prepared from tetramethyl bisphenol A (TMBPA) and 4,4'-difluorobenzophenone (DFBP), were UV irradiated on both sides in air or N 2 at 254 nm or 365 nm, which induced crosslinking and, in some cases, photooxidation. Gas permeability decreased and O 2 /N 2 selectivity increased as UV irradiation and aging time increased. At 254 nm, samples irradiated in air have lower permeability coefficients and higher selectivities than samples irradiated in N 2 , which was ascribed to additional decreases in free volume due to photooxidation in samples irradiated in air. Additionally, samples irradiated in air at 254 nm exhibit less physical aging than uncrosslinked and samples irradiated in N 2 at 254 nm, possibly due to interactions among photooxidative polar products that may restrict polymer chain mobility, thereby lowering the aging rate. The influence of water vapor on physical aging of samples irradiated in air was examined. Finally, irradiation at 254 nm leads to more extensive crosslinking and/or photooxidation than irradiation at 365 nm, possibly due to greater UV absorption by the polymer and the higher probability of radical formation at the lower wavelength.

Photostability of plasma polymerized γ-terpinene thin films for encapsulation of OPV

“…Likewise, visible (400–760 nm) and infrared (760–2500 nm) radiation do not possess sufficient energy amounts to cause significant chemical changes. UV radiation below 295 nm (UV–C) causes significant degradation but does not occur under natural conditions3334. However, a high dose of UV radiation (UV–A or UV–B) can have detrimental effects on the properties of these polymers.…”

Polymeric Membranes for O2/N2 Separation

“…5. However, long exposure to UV may cause a decrease in both O2/N2 selectivity and O2 permeability [67].…”

“…It is also possible to enhance the significant separation performance by small changes in the fabrication process, either using priming or annealing techniques [66,67]. In the priming process, the inorganic filler is firstly being enveloped with a tiny amount of polymeric solution.…”

Aromatic poly(ether ether ketone)s capable of crosslinking via UV irradiation to improve gas separation performance

“…Besides, the method is useful to improve the membrane stability and to reduce undesirable phenomena, such as physical aging 17 and plasticization 18 , which have a crucial impact on membrane durability. 11,19,20 This work examines the effect of UV irradiation on the gas transport properties of two glassy amorphous poly(ether ether ketone)s (PEEKs) lms based on diuorobenzophenone (DFB) and 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -dihydroxybiphenyl (TMBP) or 2,2 0 ,3,3 0 ,5,5 0 -hexamethyl-4,4 0 -dihydroxybiphenyl (HMBP). The monomers derived from bisphenol were chosen because the methyl groups reduce the efficiency of polymer chain packing, thereby increasing gas permeability and, moreover, they provide an abundant source of benzylic methyl groups for crosslinking reactions.…”

“…With comparative purposes, the radical derived from tetramethyl bisphenol A (M-TMBPA), and two possible radicals formed from tetramethyl bisphenol F (M-TMBPF) were also studied, because these monomers have been previously employed in the same type of reaction. 20,21 All the models are shown in Fig. 8.…”