Synthesis of high molecular weight polyimide consisting hexafluoroisopropylidene moiety for gas separation

Abstract

In this work, high molecular weight of heterocyclic aromatic polyimide consisting hexafluoroisopropylidene moiety in both diamine and dianhydride fragments was synthesised. The synthesis was performed via a two-step polycondensation route, which involved polyamic acid formation and chemical imidization. Subsequently, physical purification technique was conducted by microfiltration and re-crystallisation to obtain oligomers-free high molecular weight polymer. Selections of high purity and suitable solvent, type of amine catalyst, precipitation medium and reaction temperature were considered to favour the formation of high molecular weight polyimide. The synthesised polyimide was characterised by ATR-FTIR, which confirmed the presence of significant imide bands denoting the formation of imide linkage. Further confirmation of polyimide molecular structure was accomplished using 13 C and 1 H NMR. It was found that polyimide with high molecular weight (4500 KDa) was obtained with a polydispersity index of 1.48. Therefore, this polymer has favourable properties for gas separation membrane application.

Enhanced permeation performance with incorporation of silver nitrate onto polymeric membrane

“…In water treatment technology, membrane separation received significant advancement in this recent years and mainly subjected to its ability to remove microbes, particles and even reducing water with high heavy metal [16]. Beside, membrane filtration has also been applied in the field of food processing [17][18][19][20][21], downstream process especially for biotechnology industry [22][23][24][25], seawater treatment or desalination process [24,[26][27][28][29][30] and many other type of separations [17,[31][32][33][34]. The main reason of choosing membrane as part of the process were usually ease of operation, minimum waste generation and relatively low power needs [35].…”

Highly soluble fluorinated polyimides with promising gas transport performance and optical transparency

“…[1][2][3] PI is generally obtained from dianhydride and diamine by polycondensation, and its properties are determined by the structure of the monomers. [4][5][6][7][8] It is a representative high-performance polymer material among the most promising candidates for use as gas separation membranes due to its unique physicochemical properties, including excellent thermal stability, outstanding mechanical properties, relatively low cost, and corrosion resistance. [9][10][11][12][13][14] However, the applicability of PIs is frequently limited by their infusible, insoluble and dark color nature.…”

Studies of Formation Mechanism, Structure, and Properties of Network Copolymers Obtained by Cocuring of Rolivsan Thermosetting Resins with Aromatic Diamines

“…Thus, for example, the resonance lines at 177.5-177.8 and 173.9 ppm were assigned to the imide carbonyl in cycloaliphatic-aromatic polyimides [25]. The spectrum of aromatic (poly)amic acid contains the signals attributed to carbonyl carbon atoms at 172.80, 171.81, and 166.19 ppm [26], and the signal at 165.8 ppm [27] and 162.9 ppm [28] corresponds to the (O= 13 C-N) fragment in polyimides. In the solid-state spectra, the signal related to aromatic imide carbonyl at 166 ppm is observed; three signals at 146.6, 144.2, and 141.1 ppm can be clearly distinguished in the region typical of substituted aromatic rings [29].…”