Crosslinked copolyazoles with a zwitterionic structure for organic solvent resistant membranes

Abstract

The preparation of crosslinked membranes with a zwitterionic structure based on a facile reaction between a newly synthesized copolyazole with free OH groups and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) is reported. The new OH-functionalized copolyazole is soluble in common organic solvents, such as tetrahydrofuran (THF), dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) and can be easily processed by phase inversion. After crosslinking with GPTMS, the membranes acquire high solvent resistance. We show the membrane performance and the influence of the crosslinking reaction conditions on the thermal stability, surface polarity, pore morphology, and solvent resistance. By using UV-spectroscopy we monitored the solvent resistance of the membranes in four aggressive solvents (THF, DMSO, DMF and NMP) for 30 days. After this time, only minor changes (less than 2%) were detected for membranes subjected to a crosslinking reaction for 6 hours or longer. Our data suggest that the novel crosslinked membranes can be used for industrial applications in wide harsh environments in the presence of organic solvents.

Silane‐Crosslinked Asymmetric Polythiosemicarbazide Membranes for Organic Solvent Nanofiltration

“…This decrease can be explained by the positive charge formation at the polymer backbone and by the formation of SiOSi bonds. Similar behavior has been reported previously . The contact angles of the crosslinked membranes decreased from 61.3° to 47.3° as the reaction time increased.…”

“…They demonstrated the preparation of compaction‐free OSN PI membranes with improved chemical, thermal, and mechanical stability without the addition of a conditioning agent. Crosslinking with hybrid compounds was also reported by Chisca et al, who prepared a copolyazole polymer crosslinked with (3‐glycidyloxypropyl)trimethoxysilane (GPTMS) to form inorganic networks within the polymer matrix. The resulting ultrafiltration membranes showed excellent stability toward solvents with antifouling property due to the presence of zwitterionic structures.…”

Strengthening Phosphoric Acid Doped Polybenzimidazole Membranes with Siloxane Networks for Using as High Temperature Proton Exchange Membranes

“…Besides the organic compounds, inorganic compounds have been recently proposed as crosslinkers to fabricate crosslinked membrane electrolytes. The constituent particles could covalently crosslink with polymer backbones in order to enhance dimensional, chemical and mechanical stabilities of membrane materials . For example, Zhang and co‐workers reported a novel anion exchange membrane based on the bi‐guanidinium‐bridged polysilsesquioxane, which was fabricated via a sol–gel polymerization of an in‐house synthesized trimethoxysilane‐ended bi‐guanidinium monomer .…”

Phosphoric acid doped imidazolium silane crosslinked poly(epichlorihydrin)/PTFE as high temperature proton exchange membranes

“…PECH exhibited characteristic absorption bands at around 2850-2960 cm À1 due to the stretching vibration of methylene groups. Compared to PECH, PECH-100SiIm-Un showed the stretching vibration peaks of C]N at 1653 cm À1 and Si-O at 1017 cm À1 resulting from the imidazolium groups 26 and triethoxysilane structure, [35][36][37] respectively. Furthermore, a broad absorption bond at around 3400 cm À1 was observed for the imidazolium functionalized membranes, which was ascribed to the stretching vibrations of O-H groups, originating from the absorbed water due to the hydrophilicity of membranes.…”