Synthetic Saponite Clays as Additives for Reducing Aging Effects in PIM1 Membranes

Abstract

Polymers of Intrinsic Microporosity represent one of the most promising polymeric materials for gas separation applications. Their very rigid and contorted backbone induces unusually high free volumes and high internal surface area, with high gas permeabilities and moderate ideal selectivity, especially for O2/N2, CO2/N2 pairs with values lying above the Robeson's upper bound. However, the high FFV of PIM1 tends to be shortlived, soon collapsing to leave fewer the fillers and the polymeric matrix in addition to aging effects have been also monitored through ss-NMR spectroscopy. The 13 C spin-lattice relaxation time (T1) measurements reveal that PIM1 chains intercalation between T-O-T lamellar sheets could be one of the mechanisms responsible of PIM1 slowing down aging. Chains confinement between lamellar sheets could play a significant role in reducing chains densification, while maintaining small free volumes.

Hyper Cross-Linked Polymers as Additives for Preventing Aging of PIM-1 Membranes

“…The addition of the ABT compounds leads to an arrest in polymer aging and permeability loss. The particles incorporated within the polymer prevent the collapse of the free volume [ 22 , 25 , 27 , 33 , 34 ]. The HCPs possess a rigid network due to the high level of crosslinks which prevents the collapse of the structure.…”

“…As the aging starts, an increase in the T 1 values for the polymer carbons is expected due to the rigidification of the polymer backbone and the gradual reduction in its excess free volume [ 22 , 25 ]. This is the case in the PIM-1 membrane where the backbone carbons (C1, C2, C3, C6 and C7) have longer T 1 values at t 12 .…”

“…The addition of porous fillers in the continuous phase plays an important role in the transport properties of MMMs, providing new pathways for gas transport, hence increasing gas permeability [ 16 , 17 , 18 , 19 , 20 , 21 ]. Furthermore, the incorporation of fillers might be a solution to tackle the physical aging of glassy polymers [ 22 , 23 , 24 , 25 , 26 , 27 ].…”

Enhanced ion transport behaviors in composite polymer electrolyte: the case of a looser chain folding structure

“…The spin-lattice relaxation is sensitive to high frequency motion in macromolecular chains and mainly reflects the high frequency and short-range motion of the chains, revealing the specific nature and influence of nano-fillers on the molecular level dynamics in polymer membranes. 35 The T 1 values are related to the mobility/rigidity of the polymer. 36 It can be observed from Fig.…”

Solid State NMR Spectroscopy a Valuable Technique for Structural Insights of Advanced Thin Film Materials: A Review

“…The three aforementioned benefits were achieved with the development of thinfilm composite membranes, especially when synthesized from sustainable sources [114]. Those materials designed from an ultra-thin selective layer supported on a porous polymer template, and their applications have ranged from ionic filtration, metal cation separation and gas permeability [115,116]. Magic angle spinning (MAS) is one of the most essential and valuable techniques in solid-state NMR [117,118] since it provides high-resolution spectra not only for crystalline samples but also for amorphous ones.…”