液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚...液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚四氟乙烯(PTFE)表面,获得具有不同尺寸和间距的微/纳米锥的超疏水PTFE表面,研究射频等离子体改性PTFE表面的液滴静态接触角、滚动角及液滴撞击动力学行为,分析在不同个数液滴撞击后PTFE表面的润湿性和液滴撞击行为变化,确定PTFE表面液滴撞击起电效应的影响机制。结果表明:通过1~9个液滴撞击后,PTFE表面的静态接触角随撞击液滴数量增加而减小,导致静态接触角低于150°;液滴滚动角随撞击液滴数量增加而增大,造成液滴滚动角高于10°。撞击液滴的接触时间随撞击液滴数量增加而增大,回弹系数随撞击液滴数量增加而减小。随撞击液滴数量增加,回弹液滴的正电荷和PTFE表面的负电压增大,PTFE表面的负电荷对液滴产生强吸引作用,导致低粘附超疏水性被破坏。3 min OPT和1 min PPD改性PTFE表面的纳米锥间距小,密度大,表面负电荷量增加明显,造成PTFE表面的疏水性降低的程度最显著。研究结果可为改善超疏水稳定性的表面织构设计提供理论依据。展开更多
Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was su...Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton exchange membrane fuel cell （PEMFC）. Fourier transform infrared spectroscopy attenuated total reflection spectroscopy （FTIR-ATR） and X-ray photoelectron spectroscopy （XPS） analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy （SEM） image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion exchange capacity （IEC） of this kind of PEM was also investigated.展开更多
文摘液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚四氟乙烯(PTFE)表面,获得具有不同尺寸和间距的微/纳米锥的超疏水PTFE表面,研究射频等离子体改性PTFE表面的液滴静态接触角、滚动角及液滴撞击动力学行为,分析在不同个数液滴撞击后PTFE表面的润湿性和液滴撞击行为变化,确定PTFE表面液滴撞击起电效应的影响机制。结果表明:通过1~9个液滴撞击后,PTFE表面的静态接触角随撞击液滴数量增加而减小,导致静态接触角低于150°;液滴滚动角随撞击液滴数量增加而增大,造成液滴滚动角高于10°。撞击液滴的接触时间随撞击液滴数量增加而增大,回弹系数随撞击液滴数量增加而减小。随撞击液滴数量增加,回弹液滴的正电荷和PTFE表面的负电压增大,PTFE表面的负电荷对液滴产生强吸引作用,导致低粘附超疏水性被破坏。3 min OPT和1 min PPD改性PTFE表面的纳米锥间距小,密度大,表面负电荷量增加明显,造成PTFE表面的疏水性降低的程度最显著。研究结果可为改善超疏水稳定性的表面织构设计提供理论依据。
文摘Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton exchange membrane fuel cell （PEMFC）. Fourier transform infrared spectroscopy attenuated total reflection spectroscopy （FTIR-ATR） and X-ray photoelectron spectroscopy （XPS） analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy （SEM） image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion exchange capacity （IEC） of this kind of PEM was also investigated.
