Research On The Construction And Application Of Micro-nano Functional Materials Based On PS-b-PAA Porous Membranes

BF(Breath Figure)method is an attractive method for preparing ordered micro structure materials in recent years.The obtained honeycomb porous membrane has great application prospects in patterned templates,gas separation and removal,cell/bacterial culture,micro-containers and micro-reactors,liquid crystal display materials,super hydrophobic surfaces,separation membranes,and other fields.In order to extend this approach to a wider area,especially the rare metal materials with excellent properties and use the structural/chemical secondary processing to introduce the functional nanoparticles into the porous structures,systematic research work has been carried out in this paper and it mainly includes the following five parts:(1)Well-defined amphiphilic copolymers of PS-b-PAA were synthesized by the atom transfer radical polymerization(ATRP)and used as film-forming material for the porous membrane by BF method.Several influencing factors of the morphology of porous membranes on pattern formation such as atmosphere humidity,substrate,direction and velocity of the wet gas flow,copolymer chain segment ratio,membrane concentration,solvent,etc,were discussed in detail.While the highly ordered porous membrane is obtained,the formation law of ordered porous structures was clarified,which enriched the understanding of the mechanism of BF method.At the same time,we try to extend the BF method to the field of rare metal materials.The complexes containing rare metals were selected as the second components for film-forming material.The membranes were modified by one step blending method,and composite porous membranes containing rare metals were constructed.The unique optical properties of rare metals were well displayed in composite porous membranes.More importantly,the mixture system is relatively easy to design and has stronger versatility.It can combine functional materials with porous membranes well,accomplishes more functional modifications,and achieves a variety of functions.(2)Tin-containing composite porous membranes with honeycomb structure were prepared by blending PS-b-PAA with inorganic precursor SnCl4 by BF method.After heat treatment,the polymer was removed and tin dioxide particles with hollow open structure were obtained.As the water droplet array condensed on the surface of the solution has high affinity with the hydrolysate of SnCl4,it can be used as "micro-reactor" for the hydrolysis of SnCl4 At the same time,because of the hydrophilicity of the PAA segment,the droplets are easy to distribute around the hydrophilic chain.PS-b-PAA self-organizes around the "micro-reactor" array to form orderly porous matrix.Inorganic oxide particles with hollow open structure can be obtained by pyrolysis of in situ hydrolysates.The samples were characterized by scanning electron microscopy,energy spectrum,and X-ray diffraction.A possible mechanism for the formation of hollow open inorganic oxide particles was proposed.The gas sensing properties of SnO2 particles with hollow open structure were also studied.It was found that the hollow open SnO2 particulate gas sensing material has high sensitivity and good selectivity to ethanol gas.(3)In order to overcome the limitation of the concentration of precursor and the conditions of film formation in the mixed membrane method,a new method for preparing hollow titanium dioxide microspheres by sol-gel method with a prefabricated honeycomb porous membrane as a hard template was proposed.The hydrophilicity of PAA segments and the spatial confinement of porous templates can be used to control the hydrolysis,nucleation,growth,arrangement and crystalline form of inorganic compounds,thus forming titanium dioxide particles with special size and morphology.The effects of precursor concentration,porous membrane structure and heat treatment temperature on the morphology of TiO2 particles were investigated.Photocatalytic properties of TiO2 particles with open structure were also studied.The results showed that the degradation rate of methylene blue could reach 90%when the concentration of titanium dioxide particles was 1 mg/mL and the illumination time was 60 min.The kinetic rate constant of degradation of methylene blue by hollow open-ended titanium dioxide microspheres was 0.034-1,nearly twice as much as that of commercially available P25 titanium dioxide nanoparticles.(4)By using PS-b-PAA porous membrane as template,both chemical reduction and electrochemical deposition were used to induce in situ reduction deposition of silver,and composite porous membranes modified by silver nanoparticles with different particle size and morphology were conveniently constructed.The effects of precursor concentration,solution acidity,reducing agent dosage,deposition time and suitable complexing agent on the morphology and properties of the composite porous membrane were studied.It was found that as a general and effective method to prepare ordered structure,BF method can not only guide the realization of the ordered structure as a template but also induce the selective distribution of nanoparticles on the surface of the porous membrane.The mechanism of selective distribution of silver nanoparticles on porous films is put forward.It is pointed out that the hydrophobic effect and electrostatic adsorption effect of porous membranes are the driving force of particles to achieve directional assembly.Meanwhile,the SERS effects of R6G on composite membranes prepared by the two methods were discussed.Results indicate that the "dendritic silver"deposited by the electrochemical method has a larger specific surface area and can adsorb R6G molecule more effectively due to a large number of stereo active sites in space.A new method for preparing high-performance SERS substrates has been established.(5)Combined with the research hotspots of BF method,based on a one-step process of microporous structure,the secondary chemical component patterning and structure design were studied.On the representative of cerium oxide nanoparticles and carboxyl polystyrene nanospheres,the effects of nanoparticle type,concentration,particle size,dispersant properties and pore size on the interfacial assembly behavior of nanoparticles on honeycomb porous membrane were systematically discussed.Directional selective assembly of nanoparticles on the porous membrane surface was achieved.A simple method for constructing multi-layer micro-nano ordered structure was established and the precise control of nanoparticle assembly on the ordered 'porous membrane surface was realized.Composite porous membrane immobilized antibody,as a new type of impedance immunosensor signal amplification technology,is used in the detection of the kappa light chain.The results showed that the linearity of the immunosensor was good in the range of antigen concentration from 1.0 ×10-1 to 1.0×103 ng/mL.The linear correlation coefficient is 0.997,the detection limit is 0.05 ng/mL,and the result is satisfactory.