Synthesis of ultra-high-strength electroactive polyimide membranes containing oligoaniline in the main chain by thermal imidization reaction

• EPI membranes were prepared through a conventional thermal imidization reaction.
• Rigid aromatic structure of conjugated oligoaniline was on the backbone in EPI.
• EPI membrane was found to reveal increase of over 200% in mechanical strength.

A series of electroactive polymers of poly(amic acid) (PAA) containing aniline trimers were synthesized from electroactive diamine (amino-capped aniline trimer, ACAT), 4,4′-oxydianiline (ODA), and 4,4′-(4,4′-isopropylidene diphenoxy)-bis(phthalic anhydride) (BSAA). The prepared PAA polymers were heated to cyclize to polyimide (PI) membranes by a conventional thermal imidization reaction. The structure and electroactivity of the PIs were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV–visible spectroscopy, and cyclic voltammetry (CV). The effects of different molar ratios of ACAT and ODA on the physical properties of electroactive PI (EPI) membranes were investigated by dynamic mechanical analysis (DMA), tensile test, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The as-prepared EPI membranes showed significantly enhanced mechanical strength and thermal stability than those of non-electroactive PI (NEPI) and electroactive copolyimide (ECPI) membranes. For example, upon loading of ACAT, the tensile strength, thermal decomposition (Td) temperature, and glass transition (Tg) temperature of the EPI membranes increased by >200%, ∼45 °C, and ∼35 °C, respectively.

A series of electroactive polymers of poly(amic acid) (PAA) containing aniline trimer were synthesized from electroactive diamine (amino-capped aniline trimer, ACAT), 4,4′-oxydianiline (ODA) and 4,4′-(4,4′-isopropylidene diphenoxy)-bis(phthalic anhydride) (BSAA). The prepared PAA polymers were heated to induce cyclization, and transformed into polyimide (PI) membranes through a conventional thermal imidization reaction. Upon loading of rigid aromatic structure of conjugated oligoaniline ACAT in as-prepared EPI membrane, it was found to reveal increase of over 200% in tensile strength and Young’s modulus.Figure optionsDownload as PowerPoint slide