A Study On The Preparation And Performance Of Slippery/Superhydrophobic Energy-Saving Anti-Fouling Polymer Composite Materials

In recent years,the increase of cooling demand caused by global warming and the urban heat island effect has become a significant concern.However,traditional active cooling methods like air conditioning consume a substantial amount of energy and release pollution,leading to environmental deterioration.To solve those environment problems and achieve sustainable development,China has implemented the‘Dual Carbon’policy,which aims to save energy and reduce emissions.Passive radiative cooling technology,with its advantage of zero energy consumption and zero emissions,is widely regarded as one of the most effective approaches for energy conservation.As a result,it has gained wide attention and been studied constantly.However,current passive radiative cooling materials are susceptible to interference from external pollutants such as rainwater,accumulated dust,and microorganisms during the application process,leading to a decline in optical performance.This further results in reduced cooling efficiency,decreased stability,shortened lifespan,and increased maintenance costs,significantly impacting the large-scale application of passive radiative cooling materials.This dissertation is based on the technology of self-cleaning and anti-fouling,as well as the principles of passive radiative cooling.Two types of passive-radiative-cooling composite polymer materials with anti-fouling properties have been developed for various application environments.The comprehensive performance of those coatings,which are subjected to the synergistic effect of anti-fouling and passive radiative cooling,has been extensively investigated.For humid environments,slippery anti-fouling passive-radiative-cooling gradient materials have been developed using polymers containing urea groups.The material also possesses self-healing and recyclable characteristics.A regeneration strategy has been proposed to achieve long-lasting anti-fouling performance,allowing for in-situ regeneration through simple maintenance without removing the invalid coating.To meet the demand for anti-fouling passive radiative cooling in dry environments,superhydrophobic materials with passive radiative cooling properties have been developed,which also have the durable anti-fouling properties based on regeneration strategy.The main research topics are as follows:1.A gradient-structured composite material was made using a polymer containing urea groups,which exhibits properties such as anti-fouling,self-healing,and recyclability.The composite material consists of uPDMS（a copolymer of urea and PDMS）supramolecular polymer and dispersed Al₂O₃ functional particles as fillers.The fabrication process involves four physical processes:solvent evaporation,gelation,surface water condensation,and gravity sedimentation.These processes result in the formation of a composite material with a rough surface,consisting of an upper layer rich in polymer and a lower layer rich in particles.By spraying silicone oil onto the material,a liquid-containing slippery surface is formed due to the rough structure on its surface.This enhances the composite material’s anti-fouling performance.Additionally,the accumulation of Al₂O₃ functional particles in the lower layer gives the composite material an exceptional light scattering character,which facilitates its passive radiation cooling ability.Outdoor tests have demonstrated that the composite material provides a cooling effect that is 2℃below the surrounding environment.Furthermore,the composite material possesses self-healing and recyclability due to the hydrogen bond crosslinking within the polymer network.These properties improve the longevity and energy utilization efficiency of the material.2.This dissertation addresses the issue of ineffective anti-pollution performance in lubricating functional fluids stored in uPDMS supramolecular gels by developing a method to regenerate lubricating droplets.The aim is to create a renewable,anti-fouling,and passive radiative cooling gradient material.Droplets’self-growths were facilitated by the heterogeneous structure with varying density cross-linking formed during the gelation process of uPDMS supramolecular.The growth rate,distribution density,and volume of the droplets are controlled by regulating the reconstruction rate of the hydrogen bonds and migration rate of substances.During the growth process,lubricant molecules accumulated in weakly cross-linked polymer network.This accumulation triggered the reconstruction of hydrogen bonds in these areas,facilitating the rapid aggregation and growth of liquid molecules.As a result,micrometer-sized droplets were distributed throughout the bulk phase,forming a self-secreting supramolecular gel coating with an embedded droplet structure.This coating exhibits self-replenishment,mechanical response,and self-healing capabilities.By employing this straightforward droplet self-growth method,the issue of anti-fouling performance failure in slippery passive radiative cooling gradient materials can be addressed.Regular in-situ maintenance can preserve the coating’s anti-fouling effectiveness,extending its service life,reducing labor and material costs,and eliminating the need for coating removal.3.The use of a renewable armored structure in superhydrophobic materials can prolong the anti-fouling performance of passive radiative cooling coatings in dry environments,resulting in long-lasting cooling.This is achieved by bonding fluorinated hollow glass microspheres（HGM）with fluorinated polymethyl methacrylate resin to form a composite structure.By sanding the surface of the material,the concave cavities of the HGM are revealed,creating a rigid microscale concave structure.Simultaneously,hydrophobic fragments fell into the microscale concave structure and were fixed inside the cavities through electrostatic interaction,creating a highly rough armored structure surface with superhydrophobic properties.These hollow microspheres penetrated the entire material.When the superhydrophobic properties of the material surface faded,the rough structure can be renewed through sanding,regenerating material’s superhydrophobic properties and achieving a long-lasting anti-fouling effect.The HGM used in this composite material strengthened the matrix to form a solid armor structure and provided cavities for enhanced solar reflection and infrared emission.The coating exhibits high solar reflectance（0.93）and thermal emissivity（0.94）in the long-wave infrared window,resulting in a cooling effect of 5℃below the surrounding environment during outdoor tests.The superhydrophobic surface could be regenerated by simple sanding when the anti-fouling function faded,without compromising the passive radiative cooling function.These coatings can be produced using inexpensive materials through a single spray application,showing robust adhesion to diverse substrate surfaces and stability in different exceptional environmental.In conclusion,this dissertation aims to develop composite materials for passive radiation cooling with long-lasting antifouling properties suitable for various application scenarios.These materials offer an effective solution to the challenges encountered in passive radiation cooling technology,contributing to relieving high temperature dilemma,saving energy,reducing emissions,and promoting sustainable development.It also provides valuable guidance for academic research and engineering applications in related fields.