Design And Fabrication Of Ultralight Three-dimensional Porous Materias And Its Oil/Water Seperation Performance Study

Through billions of years of evolution,the nature organism have developed various strategies to achieve advantageous unification between its structure and bulk properties.In an effort to produce high performance oil/water seperation materials,scientists and engineers have developed many methods to construct artificial advanced materials that mimic natural architecture and function.Inspired by lotus leaves,water strider legs and hollow structure of bird bonds,an ultralight magnetic Fe2O3/C,Co/C,and Ni/C foams(with a density <5 mg·cm-3)were fabricated by pyrolyzing commercial polyurethane sponge grafted with polyelectrolyte layers based on the corresponding metal acrylate at 400 oC.The ultralight foams consisted of 3D interconnected hollow tubes that have a diameter of micrometer and nanoscale wall thickness,forming hierarchical structures from macroscopic to nanometer length scales.It was more interesting that the wall thickness and morphology of the microtubes could be tuned by controlling the concentrations of acrylic acid and metallic cations.After modification with lowsurface-energy polysiloxane,the ultralight foams showed superhydrophobicity and superoleophilicity,which quickly and selectively absorbed a variety of oils from a polluted water surface under magnetic field.The oil absorption capacity reached 100 times of the foams' own weight,exhibiting one of the highest values among existing absorptive counterparts.To extend this strategy to nonionic system to prepare ultralight foams,positively charged nanoparticles were anchored onto PU sponges grafted with polyacrylic acid firstly,after calcinations ultralight foams with density of 5-9 mg·cm-3 were obtained,The foam possessed 3D interconnected microtubes with hierarchical porous structures,the microstructure and composition of microtubes could be elaborately controlled by using different structured nanoparticles.More importantly,these foams showed superhydrophobicity after modification with siloxane,which allowed them to be used for novel aquatic devices with large loading capability and oil/water seperation.To improve the mechanical properties and extend the life span of ultralight magnetic foams,a strong and self-healing ultralight foam was prepaerd by wrapping the3 D interconnected microtubes of magnetic foams with a nanoshell of nitrocatechol substituted chitosan.Through p H-induced coordination between Fe3+ and catecholic groups,the resulting framework can spontaneously recover its configuration integrity,microstructure and mechanical properties during all 6 breaking/healing cycles.Application of the self-healing framework is demonstrated by selective separation of various oil-water mixtures.Inspired by cuticle of mussel byssal threads,a stiff and strong polymer can heal itself through dynamic metal-ligand interaction was prepared.The polymer is comprised of nitrocatechol-substituted chitosan cross-linked by catechol-Fe complexation,which exhibits a tensile strength(63.6 ± 2.2 MPa)and an elastic modulus(862.6 ± 31 MPa)comparable to or even better than those of common engineering plastics.Once suffering from multiple physical damages,the stiff polymer is able to recover its configuration integrity and mechanical properties autonomously via p H-induced coordination between Fe3+ and catecholic moiety.Moreover,the polymer also exhibits interesting renewability,flame retardance.Porous film made from the polymer.