Physical aging and carbon dioxide plasticization of thin polyimide films in mixed gas permeation

Using iron (III) acetylacetonate as both a cross-linker and micropore former to develop polyimide membranes with enhanced gas separation performance

“…However, the plasticization pressure of the pristine PI membrane occurs at CO 2 partial pressure of 12 atm while the cross-linked PI-6 wt% FeAc membrane exhibits no plasticization till CO 2 partial pressure of 20 atm. The improvement in plasticization resistance of the pristine PI membrane could be attributed to the presence of CH 4 which reduces the CO 2 plasticizing effect on the membrane [59]. Nevertheless, the high resistance of the PI-6 wt% FeAc membrane against CO 2 induced plasticization suggests that the use of iron (III) acetylacetonate as 18 both a cross-linker and micropore former may have potential to develop gas separation membranes with enhanced performance.…”

Suppression of aging and plasticization in highly permeable polymers

“…These free volume elements are less than 3-10 Å in diameter [14]. Since glassy polymers are not at thermodynamic equilibrium and possess excess free volume due to the restricted rotation of polymer chains, the interstitial space may vary with time as a result of chain motion and relaxation [15][16][17][18][19][20][21][22][23][24][25][26]. Consequently, packing density increases and the initial free volume reduces, leading to a drop in permeability.…”

“…This microstructure rearrangement towards equilibrium and permeability decay with time is often referred to as aging. Polymers with a high fractional free volume and membranes with a thinner thickness tend to have profound aging phenomenon that limits their potentials for gas separation applications [22][23][24][25][26]. Similarly, plasticization is another major challenge for glassy polymeric membranes.…”

Kinetic and equilibrium sorption of organic liquids and vapors in Matrimid

“…diffusion coefficient values as film thickness decreases. This phenomenon has been shown to occur for a variety of penetrant/polymer systems, not only for diffusion [56,61,62] but for other physical phenomena, including changes in glass transition temperature [63], polymer dynamics [64], and permeability [65][66][67]. Thickness-dependent phenomena in glassy polymer systems are often correlated to the accelerated effects of physical ageing and loss of fractional free volume (FFV) with decreasing thickness [68,69].…”