Preparation Of Zinc Sulfide And Silicon Dioxide By Using Hyperbranched Polymer As Template And Their Performance

As a?-?group wide bandgap semiconductorcompound,ZnS has been widely used in numerous fields,such as flat panel displays,solar cells,light-emitting diodes,light catalysis,and sensors et al.Mesoporous silica has good properties,including controllable pore size,good thermal stability and chemical stability,so it has wide applications in catalytic chemistry,molecular recognition sensors and other fields.It is very difficult to controlthe morphology ofzinc sulfide and silica by using traditional block polymersas templates.Hyperbranched polymer is one class ofmacromolecular polymers with highly irregular branched structures,three-dimensional conformations and intramolecular void,therefore they could be used to chelate ions,adsorb small moleculars and perform small molecular reactors.And the active ended-groups on the surface of hyperbranched polymers could be functionally modified.In this thesis,zinc sulfide and silicon dioxide were prepared by using hyperbranched polymers as templates,their morphology controllability,dimensional stability and performance were studied,and the main research contents were composed of the following contents:(1)Four different molecular weights of amino ended hyperbranched polyamides(AEHPA)were synthesized by the main materials of ethylenediamine,diethylenetriamine and methyl acrylate.The chemical structures of AEHPA were characterized by FT-IR and NMR spectrum.ZnS nanoparticles were prepared by a hydrothermal method using AEHPA-2 as template.The fators affecting the morphology of ZnS nanoparticles,including the content of AEHPA-2,reaction temperature,ratio of materials and reaction time,were discussed in detail.Three zinc sulfide nanostructures with different morphologies,including spherical,cubic and cauliflower-shaped,were obtained.Their structurefeatures,surface elements and optical properties were characterized by XRD,XPS and PL spectroscopy techniques.Size-controllablly spherical ZnS nanoparticles were prepared by using differentmolecular weights of AEHPA as templates,the effect of the molecular weight of AEHPA on the morphology,structure and optical propertiesof ZnS was tested by SEM,XRD,XPS and PL spectra.The photocatalytic degradation performance of ZnS preparedby using different molecular weightsof AEHPA were explored,and the result showsthat the ZnS prepared by using AEHPA-2 as template has the best photocatalytic performance in degradating rhodamine B solution.(2)Mesoporous silica was preparedusing AEHPA and P123 as dual templates and tetraethylorthosilicate(TEOS)as source of silicon.The effect of the content andthe molecular weight of AEHPAon the morphology of the mesoporous silica was studied,and the structure and pore size of mesoporous silica were characterized by XRD and physical adsorption and desorption tests.The result shows that increasing the AEHPA contentcan increase the specific surface area of mesoporous silica.Without adding AEHPA to the system,the specific surface area of mesoporous silica is about 634.9 m2g-1.Its total pore volume is about 1.31cm3g-1 and its BJH pore size is about 7.40 nm.When AEHPA-2is added into the system,the specific surface area of prepared mesoporous silica significantly increases,and the total pore volume enlarges slightly and the BJH pore size decreases a little.On the condition of the mass ratio of AEHPA-2 to P123 is about 2.5:1,the specific surface area of prepared mesoporous silica is about 927.7m2g-1.Its total pore volume is about 1.42 cm3g-1and its BJH pore size is about 6.10 nm.The mesoporous silicas were prepared also by using AEHPA-1,AEHPA-2 and AEHPA-3 as templates,respectively,and the result shows thatthe specific surface area,the total pore volume and the BJH pore size of mesoporous silica will reduce with the increase of molecular weight of AEHPA.The mesoporous silica using AEHPA-1 as template has the biggest specific surface area about 916.9 m2g-1.Its total pore volume isabout 1.41 cm3g-1and its BJH pore size is about 6.15 nm.While the mesoporous silica using AEHPA-3 as template has the smallest specific surface area about 671.4 m2g-1.Its total pore volume is about 0.98 cm3g-1and its BJH pore size is about 5.82 nm.(3)Mesoporous silica was prepared by using AEHPA-2 as a template,ethanol and water as media and TEOS as a silicon source by a sol-gel synthesis.The morphology,structure and pore characteristic of prepared mesoporous silica were charactered by TEM,XRD and physical adsorption-desorption tests successively.The result indicates that the surface area,total pore volume and pore sizeof the prepared mesoporous silica are all quite large and it has narrow pore size distribution.The specific surface area of prepared mesoporous silica is about 487.4 m2g-1.Its total pore volume is about 0.37 cm3g-1andits BJH pore size is about 3.04 nm.(4)Porous silica microsphere was parepared by using terminal carboxyl hyperbranched polyester(Hyper C102)as a template,dioxane and ammonia as media and TEOS as a silicon source.The morphology and pore size characteristic of prepared silica microsphere were charactered by TEM and physical adsorption-desorption tests.The factors affecting the morphology of silica microsphere,including the content of Hyper C102,the amount of distilled water,the proportion of ammonia and water and the content of TEOS were all discussed in detail.The result shows that without Hyper C102,the diameter of prepared silica sphere is about 500 nm and it is non-porous structure.When Hyper C102 is added,the diameter of prepared silica sphere decreases to 200 nm and the silica sphere has an obvious pore structure.The specific surface area of prepared silica sphere is about 15.18 m2g-1.Its total pore volume is about 0.05558 cm3g-1 and its BJH pore size is about 14.65 nm.