| The icing phenomenon caused by low temperature poses a serious threat to human production and life.The superhydrophobic surface as a safe and efficient new anti-icing method has been highly expected in recent years,especially the combination of superhydrophobic surface and photothermal materials to realize the combination of passive anti-icing and active de-icing function has shown great application potential.However,there still exist problems of high cost of preparation methods and imperfect wetting theory regarding superhydrophobic surfaces and unclear mechanism of temperature response during photothermal conversion regarding photothermal materials.In this thesis,by preparing polypropylene(PP)surface micro-nano structure and adding graphene(GP)as photothermal particles,a superhydrophobic surface with excellent photothermal performance of PP-based composites is prepared,which realizes the effective combination of superhydrophobic passive anti-icing and photothermal active de-icing functions.The effects of microstructure on its surface wetting performance and the effect of GP content on the photothermal conversion performance of its composites were discussed from a theoretical perspective.Anodic aluminum oxide(AAO)templates with different pore sizes and pore densities are prepared,and the corresponding nanostructures are replicated on the PP surface by a hot imprinting process.It is found that both increasing the size and the array density of nanostructures can improve the hydrophobic properties of the surface.According to the three-phase contact line theory,this is due to the increase of contact line density(?cl).The data fitting shows that the contact angle(CA)of the single-scale structure surface exhibited a second-order decay exponential relationship with its?cl,and the rolling angle(RA)also gradually approached 0°with the increase of its?cl.The maximum?cl of the prepared nanostructure is 11.91×10~4 cm-1,and its superhydrophobic performance is the best(CA was 163.7°,RA was 0.9°).The AAO templates with micro-nano structures are prepared by micron imprinting and combined with anodic oxidation process,and then the corresponding micro-/nano structures are prepared on the PP surface by hot imprinting process.The micron structure combined with nanostructure can further enhance the superhydrophobic performance of the surface,where the higher?cl of nanostructure is more conducive to enhancing the wetting stability of the surface.The optimized micro-/nano structure surface has a CA of162.7°,RA of about 0.2°,surface adhesion of only about 4?N,excellent dynamic wetting performance,almost no contact angle hysteresis,and excellent droplet impact resistance and water immersion resistance.The photothermal PP composites with different GP contents are prepared by melt blending method.It is found that the addition of GP leads to a substantial increase in the light absorption of the composites in the full wavelength range.Among them,the highest light absorption is achieved when the GP content is 1 wt%,which is generally higher than95%in the full wavelength range.From the perspective of energy conversion combined with Newton's law of cooling,it is found that the photothermal conversion performance of composites is positively correlated with the ratio of their light absorption and thermal conductivity.Due to the high thermal conductivity of GP,the thermal conductivity of the composite increases with the increase of GP content.When the GP content is 1wt%,the ratio of light absorption and thermal conductivity reaches the maximum value of about3.84,and the surface reaches the maximum temperature and stabilizes at 96°C after 5 min of one sun irradiation.And there is a slight decrease in the anti-icing property of the composite surface since the thermal conductivity of the composite is increased.Nanostructures and micro-/nanostructures are prepared on the surface of composites with a preferred GP content of 1wt%.It is found that both increasing the?cl of nanostructure and constructing micro-/nanostructure can enhance the anti-icing performance of the surface in low temperature and high humidity environment,where increasing the?cl of nanostructures is more critical for the improvement of anti-icing performance.Among them,microstructure combined with higher?cl nanostructure can maximize the retention of nanoscale and microscale air pockets and so improve the thermal resistance between the interfaces,thus enhancing the anti-icing performance of the surface.The freezing time of the droplets on the surface of the preferred micro-/nanostructure is 214 s,which is about one time longer compared to the flat surface,and the melting time is 73 s under one sun irradiation,which is 23%shorter compared to the PP flat surface. |
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