Synthesis And Application Of Interconnected Hierarchical Porous PolyHIPEs And Their Composites

High internal phase emulsions(HIPEs)can be used to prepare highly interconnected porous polymer foams(polyHIPEs).Because of their outstanding advantages such as hierarchical porous structure,low density,high porosity,large specific surface area,good material transport capacity,rich chemical composition,easy functional modification,flexible design of pore structure and shape,polyHIPEs are widely used in heavy metal separation and chromatographic analysis,adsorption,catalysis,sensing,molecular recognition capture,biological tissue engineering and environmental science fields.Although there have been many research reports on polyHIPEs in recent years,there are still many aspects worth studying.Moreover,the polyHIPEs are generally bulk materials,which are not as convenient as particulate materials in many applications.This thesis hopes to expand the preparation of polyHIPEs and their applications in various fields.In this thesis,highly interconnected porous polymer foams prepared by radiation polymerization of water-in-oil HIPEs are used as a platform to synthesize various porous materials with different compositions and different morphologies(such as blocks and microspheres)by monomer regulation and structure design.Then,the porous polymer materials are further functionally modified for different applications.We hope to provide an idea for flexible design and efficient utilization of porous polymer materials by giving full play their advantages.The main contents of this thesis are summarized as follows:(1)Radiation synthesis and hydrophilic modification of polyHIPEs.The better content of the crosslinking agent DVB in the radiation polymerization of St-DVB HIPE is 15?25%of oil phase.And both hydrophilic and lipophilic P(St-MAH-DVB)or lipophilic P(MMA-MAH-DVB)polyHIPEs which can improve hydrophilicity by further hydrolysis,are prepared by adding malay substitution(MAH)to the St/DVB or MMA/DVB HIPEs using Span 80 as an emulsifier.Alternatively,hydrophilic materials with double polymer networks can be prepared by adding acrylic acid(AA)to the dispersed phase of conventional HIPEs,in which the best mass ratio of EHA and AA is 4:1.The prepared flexible PEHA-PAA can be used for adsorption and separation applications.(2)PolyHIPEs can be used as a carrier for MOFs catalysts.After P(MMA-St-DVB)-polyHIPEs is modified by sulfonation of concentrated sulfuric acid and hydrolysis in strong alkali,HKUST-1@SP(MAA-St-DVB)can be prepared by alternately soaking HKUST-1 precursor solutions using SP(MAA-St-DVB)-polyHIPEs as the carrier.Then,the oxidation reaction of diphenylmethane(0.250 mmol)in the presence of the oxidant TBHP(0.625 mmol)and the solvent benzonitrile(1 mL)was studied catalyzed by HKUST-1@SP(MAA-St-DVB).It is found that the optimal reaction condition is using 30 mg catalyst to react 14 h at 80?.The supported catalyst HKUST-1@SP(MAA-St-DVB)has good catalytic performance and excellent cycling stability,while the conversion rate of pure HKUST-1 particles is significantly reduced after five cycles.Therefore,our strategy provides a new approach for the recyclable application of MOFs and the preparation of supported catalysts for reactors of various shapes.(3)Radiation synthesis and application of polyHIPE microspheres.In the case of DVB as a cross-linking agent,the polyHIPE microspheres with different compositions and size can be adjusted by introducing different acrylic monomers,especially fluorine-containing acrylic monomers,and changing experimental conditions such as stirring speed,water phase content,etc.Moreover,the modification of polyHIPEs microspheres can be achieved by different methods.For example,silver nanoparticles are loaded into polyHIPE microspheres for use as antimicrobial agents,and the superhydrophobic surface can be directly constructed by polyHIPE microspheres.It provides the possibility for the realization of various applications of polyHIPEs microspheres.(4)Preparation and application of superhydrophobic separation membrane.We provide an easy-to-operate method for constructing a fluorine-free superhydrophobic separation membrane by filtrating the dispersion of different hydrophobic polyHIPE microspheres on stainless steel meshes.The performance of as-prepared separation membrane is characterized by the wettability,oil flux,penetration pressure,separation efficiency,and cycling stability.The oil-water separation results show that polyHIPE microspheres@stainless steel meshes have excellent oil-water separation efficiency(about 99.5%)and outstanding permeation flux(no less than 187.5 L/(m2·min)and the maximum value of 1850 L/(m2·min)),and they can still maintain excellent separation efficiency and stability after 10 cycles in corrosive environment.This feasible synthesis method has a wide range of potential applications in the large-scale fabrication of different types of superhydrophobic or superoleophilic materials.Moreover,we tested the fluxes of 12 kinds of separation membranes for different oil solvents,indicating that the flux can be adjusted by changing the composition of the microspheres and their coating thickness.These provide data support for practical applications.(5)Preparation and application of heteroatom-doped porous titanium dioxide microspheres.A series of porous TiO2 microspheres composed of nanocrystals doped by heteroatoms were synthesized by a simple sol-gel method combining with calcination and hydrothermal method using polyHIPEs microspheres as templates.The effects of different non-metallic heteroatoms on the morphology,crystal phase,optical properties and photocatalytic activity of porous TiO2 microspheres were studied by means of SEM,TEM,XRD,XPS,PL and IR.It is found that the doping of non-metallic heteroatoms into porous TiO2 microspheres could increase their photocatalytic activities for the degradation of RhB under visible-light illumination,and the C-,S-,N-doped titania(C/S/N@TiO2)porous microspheres have the best photocatalytic performance.The doping of non-metallic heteroatoms can narrow the forbidden band width of TiO2,improve the optical absorption in the visible region,and promote the separation and transfer of carriers to a certain extent.In addition,hierarchical porous structure can enhance light absorption,facilitate material transport,expose more active sites,and thus improve the catalytic activity.By adding different free radical scavengers,it is found that OH and h+play an important role in the degradation of RhB.