Synthesis, characterization, and CO₂ permeation properties of acetylene‐terminated polyimide membranes

Abstract

A novel fluorine‐containing telechelic polyimide end‐capped with acetylene group which derived from 4,4‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,4‐diaminodiphenyl ether (DADE), and 4‐(2‐phenylethynyl) phthalic anhydride (PEPA) was synthesized using polycondensation. The physical and CO2 permeation properties of its crosslinked membranes prepared by the cyclotrimerization reaction of the acetylene groups at the polymer chain end using tantalum (V) chloride (TaCl5) as a catalyst under thermal treatment was investigated in terms of CO2‐induced membrane plasticization. The crosslinked membranes showed a gel content in organic solvent, which was good solvent of noncrosslinked membranes, and improved their thermal stability. Based on the measurement of the high‐pressure time dependence on CO2 permeation, the crosslinked 6FDA–DADE–PEPA membranes exhibited more resistance to CO2‐induced plasticization than noncrosslinked 6FDA–DADE and thermal treated 6FDA–DADE–PEPA. Furthermore, the increase in TaCl5 content resulted in more resistance to plasticization. The cyclotrimerization reaction of the acetylene groups at the polymer chain ends using a transition metal catalyst under thermal treatment was found to be more effective than conventional thermal treatments for suppressing membrane plasticization without the membrane densification. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Synthesis and characterization of ABA‐type triblock copolymers derived from polyimide and poly(2‐methyl‐2‐adamantyl methacrylate)

“…The wavelength of the radiation was 1.54 Å. The d ‐spacing was calculated according to Bragg's conditions, this parameter denoting the mean distance between the polymer chains …”

“…Aromatic polyimides (PIs) are widely used as structural, electronic and optical materials because of their good thermal stability, mechanical strength and optical properties . In particular, fluorine‐containing PIs, such as 4,4‐hexafluoroisopropylidenediphthalic anhydride (6FDA)‐based PIs, have higher thermal stability, mechanical strength, gas permeability and gas selectivity than other PIs because of the presence of a trifluoromethyl group of high free volume …”

Developing Highly Tough, Heat-Resistant Blend Thermosets Based on Silicon-Containing Arylacetylene: A Material Genome Approach

“…For example, the PSA resins were modified by dipropargyl ether from melt blending or blended with benzoxazines to improve the toughness. , Despite a series of attempts, there is still a gap from the expected performanceeither the thermal stability is significantly decreased or the toughness is not sufficiently improved. Polyimide, especially thermosetting polyimide capped by reactive end groups, shows excellent comprehensive properties such as pretty good thermal stability, high toughness, and strong adhesion with reinforced fibers. − Compared to the PSA resins, the polyimides exhibit lower thermal stability but better mechanical properties. Because the PSA resins contain alkynyl groups, − the acetylene-terminated polyimide can be selected as a blend to toughen PSA resins via the reaction of the terminal alkynyl groups of two resins during the curing process.…”

Thermally induced chemical evolution in polyimide films investigated by X‐ray photoelectron spectroscopy

“…Among the many methods reported for improving some specified propriety of these PIs , thermal treatment seems to be a promising direction for building materials with tuneable porous structures besides allowing for easy up scaling. For example, there have been independent reports of PI modification obtained using a post‐synthesis step of thermal treatment either under an oxidizing (O 2 or air) or an inert (vacuum, nitrogen, or argon) atmosphere .…”