Study On Preparation And Properties Of Dual-responsive Superhydrophobic Materials

Superhydrophobic materials have been extensively studied due to their special wetting properties,but there are also some problems such as the use of environmentally unfriendly fluoride substances and low adhesion between coating and substrate.Oily wastewater from industrial production has a negative impact on the environment,and current methods for separation are complex and costly.Therefore,it is of great significance to prepare intelligent and responsive superhydrophobic coatings with good durability using low-cost and environmentally friendly materials.Triblock copolymer was synthesized from 3-(trimethoxymethylsilyl)propyl methacrylate(TSPM),butyl methacrylate(BMA)and ethyl methacrylate(HEMA).Then the fluorine-free superhydrophobic coating was obtained by blending with silica nanoparticles/polydimethylsiloxane(SiO2 NPs/PDMS)and applied to paper surface by dipping.SEM was used to prove that the surface roughness of the modified coating increased effectively.1H NMR and FTIR were used to analyze the polymer structure.XPS results showed the change of surface composition.The self-cleaning and mechanical wear resistance of the paper surface were verified by performance test.In order to obtain responsive superhydrophobic paper,the pH-responsive monomer 2-(dimethylamino)ethyl ester(DMAEMA)was introduced to synthesize copolymer which was blended with SiO2 NPs/PDMS to obtain pH-responsive superhydrophobic paper.The contact angles of paper at different pH values were measured,and the results showed that the paper could keep its superhydrophobic state under the neutral and alkaline environment,but would change to the hydrophilic state under the acid condition.The efficiency,flux and circulation of oil-water separation were analyzed,and the results showed that the separation efficiency of modified paper can still be more than 98%after more than 30 separation cycles.In order to further study the response function,the temperature response monomer N-isopropyl acrylamide(NIPAm)was introduced to obtain a superhydrophobic paper with both pH and temperature response function.The lower critical solution temperature was determined to be 25?.The hydrophilic and hydrophobic states of paper at different temperatures and pH values were studied and the results showed that the paper maintained superhydrophobic surface at 25? and medium alkaline conditions,whereas it was hydrophilic.