Polyimide Membranes Derived from Poly(amic acid) Salt Precursor Polymers. 1. Synthesis and Characterization

Abstract

A series of new poly(amic acid) salt polymers were synthesized and characterized. It has been found that these poly(amic acid) salt polymers are highly soluble in alcohol-based solvents, a feature that is useful for membrane preparation. It was also found that poly(amic acid) tertiary amine salts can be quantitatively imidized at 150 °C, a temperature that is lower than the imidization temperature of poly(amic acid) or of poly(amic acid) quaternary amine salts of identical backbone structure. This makes poly(amic acid) tertiary amine salt polymer a preferred precursor for preparation of polyimide gas separation membranes. Gas permeation characteristics of dense polyimide films prepared from poly-(amic acid) tertiary amine precursors were further measured and compared to chemically identical polyimide films obtained by conventional methodologies.

Synthesis and characterization of modified bismaleimide/polysulfone semi‐interpenetrating polymer networks

“…Comparing the performance of these novel membranes with reported patents, it is clear that obtaining high O 2 /N 2 selectivity of 4.3, the oxygen permeance would not exceed 34 GPU as reported elsewhere. 65 However as reported elsewhere, 66 there was a decrease in selectivity of oxygen over nitrogen to 1.5 when permeance reached 127 GPU which could be attributed to the traditional trade off known for most polymeric materials used in gas separation membranes. 67 The gas permeance for PSF-BMI-EtOH-L was 553 GPU that included 366 GPU of pure oxygen in the mixture with a calculated selectivity of 2.1 as shown in Table IV.…”

A water-soluble polyimide precursor: Synthesis and characterization of poly(amic acid) salt

“…Since poly (amic acid)s are soluble only in strongly polar solvents as mentioned above, which are toxic, careful handling is necessary to avoid environmental problems. Moreover, due to the hydrolytic instability for PAAs over storage, there have been efforts to prepare other precursors of polyimides, such as poly(amic acid) esters, 1-2 and poly(amic acid) salts (PAAS), [3][4][5][6] which have no storage problem in solution. Especially, compared to poly(amic acid) and poly(amic acid) ester, PAAS is attractive because it is easy to synthesize and is soluble in water, which are beneficial for both the environmental and practical issues.…”

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We have synthesized a water-soluble polyimide precursor, poly(amic acid) amine salt (PAD), from pyromellitic dianhydride (PMDA),4, and N, and have investigated in detail its properties with respect to the degree of salt formation (D sf ). The maximum value of D sf we obtained upon precipitation of the precursor solution into acetone was 79%.

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Synthesis and characterization of high performance poly(thioether imide)s via aromatic nucleophilic substitution reaction of isomeric AB-type monomers

“…However, tetracarboxylic dianhydrides and diamines are highly expensive and need multisteps to synthesize; meanwhile, tetracarboxylic dianhydrides are tend to hydrolyze and diamines are easily to be oxidized in the process of preservation. What is more, the intermediate polyamic acids in solution are known to be notoriously unstable and tend to depolymerize even at room temperature in storage for long period, because hydrolytic cleavage reaction readily takes place [7][8][9][10][11].…”