Bangkun Jin

A novel poly(2,6-dimethyl-1,4-phenylene oxide) with trifunctional ammonium moieties for alkaline anion exchange membranes

2,4,6-Tri(dimethylaminomethyl)-phenol was synthesized as a trifunctional moiety and incorporated onto poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) to obtain a novel quaternary ammonium functionalized PPO (PPO-TQA). Membranes of the polymer were fabricated and exhibited high conductivity, a low swelling ratio and water uptake.

Hydroxide-conducting polymer electrolyte membranes from aromatic ABA triblock copolymers

A new ABA triblock copolymer (QPPO-PAES-QPPO) was successfully synthesized by combining one block of poly(arylene ether sulfone)s (B, PAES) and two blocks of quaternary ammonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (A, QPPO). Membranes of the triblock copolymer with distinct nanophase separation showed high performance.

Preparation and characterization of composite membranes with ionic liquid polymer-functionalized multiwalled carbon nanotubes for alkaline fuel cells

Multiwalled carbon nanotubes functionalized with an imidazolium-type ionic liquid polymer, PIL(BF4)–MWCNTs, have been successfully prepared via in situ free radical polymerization of 1-vinyl-3-methylimidazolium iodide ([VMIm][I]) and then blended with poly(2,6-dimethyl-1,4-phenylene oxide) containing imidazolium groups (PPO–MIm) in solution to fabricate composite membranes. The composite membranes were characterized by scanning electron microscopy (SEM) and the SEM images of the membranes show that the PIL(BF4)–MWCNTs can be homogeneously dispersed in the PPO–MIm matrix. The conductivity and mechanical properties of the composite membranes were examined. It was demonstrated that the incorporation of the PIL(BF4)–MWCNTs into the membranes of PPO–MIm can increase both conductivity and mechanical properties. The composite membrane containing 0.3 wt% of PIL(BF4)–MWCNTs (P(0.3)) exhibits a dramatic enhancement in ionic conductivity (95.3%) and tensile strength (82.9%) in comparison with the membrane without PIL(BF4)–MWCNTs. Therefore, this research demonstrates that the incorporation of functionalized carbon nanotubes is a facile and useful strategy for improving both ionic conductivity and mechanical properties of alkaline polymer electrolyte membranes.

A facile and highly efficient strategy for esterification of poly(meth)acrylic acid with halogenated compounds at room temperature promoted by 1,1,3,3-tetramethylguanidine

Esterifications of poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA) have been investigated with a wide variety of halogenated compounds such as iodide, bromide, and chloride using 1,1,3,3-tetramethylguanidine as a promoter. The results demonstrate that the poly(meth)acrylates can be obtained with an excellent degree of esterification at room temperature. The influence of solvent, reaction conditions, and halogenated compounds on the esterification reaction was examined. It was found that polar solvents, such as dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), are favorable for the esterification and high degree of esterification can be achieved in a short time. Moreover, the esterification reaction of PMAA has been successfully performed in an aqueous solution of DMSO, which indicates that the solvent does not necessarily have to be dried for this reaction. Primary and secondary halogenated compounds can successfully react with PMAA or PAA, while tertiary halogenated compounds fail to react. In addition, combining this esterification reaction with atom transfer radical polymerization (ATRP), macromonomers were conveniently prepared by the reaction of halogen-capped polymers with methacrylic acid under mild conditions.

A novel poly(2,6-dimethyl-1,4-phenylene oxide) with pendant imidazolium groups for high-temperature proton exchange membrane

We designed and synthesized a novel poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with imidazolium-functionalized aromatic side chains by the reaction of imidazole-functionalized PPO and methyl iodide, and then prepared the acid doped PPO membrane by immersing the polymer membrane in phosphoric acid (PA). To achieve a high acid doping level and a high dimensional stability, the cross-linked membranes were prepared by the reaction of the imidazole groups of the polymer and 1,4-bis(bromomethyl) benzene. The PA content, area swelling, and tensile strength of the non-crosslinked and the crosslinked membranes doped with a H3PO4 solution were measured. The results showed that the crosslinked membrane with a PA content of 438% possessed the highest conductivity of 54 mS cm−1 at 140 °C with high dimensional stability and high tensile strength. Moreover, no shape change of the membranes was observed in 15 days in a Fenton solution containing 3% H2O2 and 4 ppm Fe2+ at 80 °C, indicating a high oxidative stability. Therefore, this new polymer can be considered as a promising candidate for preparing a high temperature proton exchange membrane for use in fuel cells.

Xanthate-mediated living/controlled radical copolymerization of hexafluoropropylene and butyl vinyl ether under 60Co γ-ray irradiation and preparation of fluorinated polymers end-capped with a fluoroalkyl sulfonic acid group

Living/controlled radical copolymerization of hexafluoropropylene and butyl vinyl ether has been successfully achieved at room temperature under 60Co γ-ray irradiation in the presence of ethyl 2-(ethoxycarbonothioylthio) acetate. The copolymer end-capped with a sulfonic acid group has been prepared by oxidation of the xanthate end group.