Preparation Of Core-shell Porous PVDF@PS And Its Functionalized Electrospun Fibers And Its Adsorption Properties

The pollution arising from oil spills and organic compounds are a matter of great concern due to is damaging impacts on the ecological environment.Generally a series of efficient and reusable adsorbent materials,which could be easily removed from the pollutant are fast-growing.More recently,electrospinning PS fibers as oil sorbents were investigated,but the poor mechanical properties of electrospinning PS fibers limited its application in oil cleanup from water.β-CD consist of cyclic oligosaccharides that present a doughnut shape.The internal part of the CDs acts as a hydrophobic cavity,while the exterior part has a hydrophilic character,because of the presence of many hydroxyl groups.The dimensions of the cavity are compatible with the formation of “host–guest”compounds with molecules that present lipophilic groups.As these phenomena of molecular inclusion are reversible,the guest molecule can be released from the complex without any change of its properties.The purpose of this study was to develop a kind of coaxial electrospun PVDF@PS fibers with better mechanical properties based on PS solution as the shell solution and PVDF solution as the core solution.Furthermore,porous electrospun PVDF@PS fibers are functionalized by in situ polymerization a thin layer of PDA and subsequently attaching β-cyclodextrin(β-CD)on the surface.ith abundant catechol groups,the PDA layer allows facile attachment of b-CD on the fiber surface by multiple hydrogen bonding.The fine structures of coaxial electrospun PVDF@PS fibers were regulated by manipulating the core solution flow rate and viscosity.The higher viscosity difference between the core and shell solutions and suitable flow rate of core solution were beneficial to the formation coaxial structure.Morphology of PVDF@PS fibers largely depended on the rate of solvent removal from the charged fluid jet on its surface and environmental humidity.While increasing the humidity from 10% to 60%,the resultant electrospun fibers exhibited a change in shape and surface morphology,from a circular no pore to ribbon-like porous fibers.Meanwhile the amount and size of pores were also growing.Efforts have been made to improve the mechanical properties of PS fibers.When the coaxial electrospun procedure was applied with 0.6ml/h core solution and 30%humidity,the mechanical properties of PVDF@PS were further improved.The tensile strength and elongation to break were up to 14 times and 9 times respectively comparing with PS fibers.According to DSC and FTIR measurements,these improvement onmechanical properties could be ascribed to the independent surrounding for PVDF and PS to keep their advantages among the coaxial electrospun fibers.The good hydrophobicity–oleophilicity facilitated the oils to be soaked out conveniently,and the sorption capacities for silicon oil were 29.51g/g.With abundant catechol groups,PDA layer allowed facile attachment of β-CD on the surface of PVDF@PS/PDA fibers to achieve the functionalized PVDF@PS/PDA/β-CD.The PVDF@PS/PDA/β-CD fibers could effectively remove 90% phenol from aqueous solutions,which can be accomplished by inclusion from the cavity of β-CD,and interaction with active groups of PDA.In addition,PVDF@PS/PDA/β-CD fibers can be easily regenerated by washing with low-cost alcohol.Thus PVDF@PS/PDA/β-CD fibers have great potential to be used in water detoxication for the removal of phenol molecules.