Gong Xiaodong,Luo Huan,Liu Gang,Luo Cong,Niu Yanhua,Li Guangxian
The gel polymer electrolytes (GPEs) with poly(acrylonitrile-polyhedral oligomeric silsesquioxane)/poly(vinylidene fluoride) (PAN-POSS/PVDF) blends as free-standing porous membrane and ionic liquid (IL) as absorption substance were successfully prepared. By tuning the content of PAN-POSS, the porosity and absorptivity of the blended membranes could be regulated. Due to the higher porosity and absorptivity, the ionic conductivity of GPEs with 15 wt% PAN-POSS reaches to 1.91 × 10 −3 S cm −1 at 20 o C. Meanwhile, the electrolytes also show excellent mechanical properties, thermal stability, and fire resistance. More importantly, the high electrochemical window of 4.6 V (vs. Li/Li + ) has been acquired and the testing cells with Li metal anode and LiFePO 4 cathode show a tolerable rate performance. Such prepared GPEs are expected to be applied to lithium batteries with high safety and electrochemical performance.
Membrane fouling and wetting were two unsolved issues for membrane distillation (MD), fostered an enduring pursuit of well-designed superhydrophobic membrane. In this work, a novel hierarchically-structured superhydrophobic membrane was prepared by grafting octavinyl-polyhedral oligomeric silsesquioxane (OVPOSS) onto polyvinylidene fluoride (PVDF) membrane via UV-induced thiol-ene click reaction after the hydroxylation and sulfhydrylation pretreatment . The POSS/PVDF membrane exhibited high roughness and superhydrophobicity, and the pore structure was optimized with smaller size but centralized distribution. For the fabricated superhydrophobic membrane with low sliding angle (about 7.5°), the maintaining of Cassie-Baxter state and the “slip effect” significantly mitigated membrane fouling and wetting, due to the retardation of the liquid invasion into the gas-solid interface. It was found that scaling was the leading fouling for the commercial PVDF membrane, and the interaction between Ca 2+ and carboxyl was the main organic fouling mechanism . While for the POSS/PVDF membrane, organic fouling via hydrophobic-hydrophobic interaction was the main membrane fouling and the scaling was significantly alleviated. The fabricated POSS/PVDF composite membrane had significant superiority over commercial PVDF membrane, which showed promising potential in challenging wastewater treatment . Additionally, this work also offered a new and facile method for superhydrophobic membrane fabrication.
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