The preparation of self-supporting anion exchange membranes with enhanced mechanical strength and ultrathin thickness is still a challenge to improve the performance of fuel cells. In this work, we developed 9-dodecylidene-9H-fluorene (DDF) as a branched monomer to construct branched structures based on poly(arylene piperidinium)s. After introducing a 2.5% molar ratio of DDF, quaternized poly(piperidinium-triphenyl-dodecylidenefluorene) (PPTDF-QA) possesses low water swelling (below 25% at 80 °C) and high mechanical strength (over 70 MPa). The obvious phase-separation behavior of the branched membranes induced by the long alkyl chain improves hydroxide conductivity which reaches 168 mS cm−1 at 80 °C. Meanwhile, the thickness of branched PPTDF-QA can be optimized to 8 μm. The present work reveals that a facile branched monomer can promote the formation of a microphase-separated morphology of the membrane to fabricate high-performance anion exchange membranes.
Emergency situation of electromagnetic microwave pollution generated by daily electronic devices urgently requires light-weight and efficient microwave absorption materials with thin thickness and low filling ratio. Herein, the heteroatoms-doped Fe 3 C@C nanofibers are fabricated from a mixture solution of Iron (III) 2, 4-pentanedionate (Fe(acac) 3 ) and nitrogen-containing polymer poly (phthalazinone ether nitrile ketone) (PPENK) by electrospinning and the following thermal treatment. The morphologies and compositions of nanofibers can be controlled by annealing temperature. The 1-Dimensional (1D) heteroatoms-doped Fe 3 C@C nanofibers display outstanding microwave absorption performance. When the filling ratio is 30 wt% in paraffin for nanofibers heat-treated in 700 ℃, the optimal reflection loss value is − 35.5 dB at 8.3 GHz with a thickness of 2.8 mm. Additionally, the maximal efficient absorption bandwidth reaches as wide as 4.9 GHz ranging from 13.1 to 18.0 GHz with a rather thin thickness of 1.6 mm. The Fe 3 C@C nanofibers have adjustable electromagnetic parameters and thus, balance impedance matching and microwave attenuation performance at the same time. This work investigates the relationship between microwave absorption performance and the chemical states of nitrogen atoms, revealing a facile strategy to prepare a multi-interface microwave absorber and presenting a candidate application for microwave absorption materials with low matching thickness.
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