Preparation Of Mesoporous Titanium Dioxide Using Modified F127 Block Copolymer As Template

With the aggravation of environmental pollution,the decrease of petroleum,coal and natural gas resources and the increase of energy demand,people pay more and more attention to new energy technology and energy conversion and storage.Although great progress has been made in energy technology and energy conversion and storage,there are still many problems to be solved.Mesoporous titanium dioxide?titanium dioxide?has high specific surface area,well-developed pore structure,adjustable pore size in a certain range,and easy surface modification.It has wide application prospects in water treatment,air purification,solar cells,biological materials and so on.However,the disadvantages of titanium dioxide are that it can only absorb ultraviolet light,which leads to the solar energy couldn't be used effectively,the activity of photocatalyst is low,nanoparticles are easy to aggregate,separation and recovery are difficult.It is still a challenge to prepare high performance mesoporous titania with adjustable pore size,high specific surface area,high crystallinity and high thermal stability.?1?Triblock copolymer F127(EO₁₀₆PO₇₀EO₁₀₆)was modified.The end-hydroxyl group of amphiphilic block copolymer F127 was reacted with compounds containing isocyanate functional groups to form F127 with isocyanate termination.The PEI-F127-PEI multiblock copolymer was obtained by reacting with polyamine-containing polymer polyethylenimide?PEI?.The block copolymers of PEI-F127-PEI have been successfully prepared by the characterization of FTIR and NMR.The size of F127 micelles modified by PEI increased through dynamic light scattering.?2?Mesoporous titanium dioxide nanoparticles were prepared in nitrogen and air atmosphere using PEI-F127-PEI block copolymer as template.Mesoporous titanium dioxide was prepared by evaporation-induced self-assembly and calcination in different atmosphere when PEI-F127-PEI block copolymer was used as template.The presence of amines acts as a complexing agent.By adjusting the mass ratio of precursors and PEI-F127-PEI,the range of amino coordination can be changed.Different crystal forms which including rutile,anatase and mixed crystalline,are obtained.The results show that the morphology of mesoporous titanium dioxide nanoparticles prepared in nitrogen atmosphere changes from long-range ordered mesoporous structure to massive mesoporous structure with the increase of the content of titanium precursor.In the experiment of photocatalytic degradation of organic dye methylene blue?MB?,when the mass ratio of titanium dioxide/PEI-F127-PEI is 2.4/1,the photocatalytic degradation effect is the best.With the increasing content of titanium precursor,the morphology of mesoporous titanium dioxide nanoparticles prepared in air changed from granular mesoporous structure to bulk structure.The average pore size of mesoporous titanium dioxide obtained by BET test was 16.3 nm.It was found that the photocatalytic degradation of organic dye methylene blue?MB?was the best when the mass ratio of titanium dioxide/PEI-F127-PEI was 2.0/1?mixed crystalline mesoporous titanium dioxide?.?3?Copper-doped mesoporous titanium dioxide nanoparticles and Vanadium-Doped mesoporous titanium dioxide nanoparticles were prepared using PEI-F127-PEI block copolymer as template.By adjusting the amount of titanium precursor,mesoporous doped titanium dioxide with long-range ordering was prepared by evaporation-induced self-assembly and calcination.The experimental results show that when the molar ratio of precursor and PEI-F127-PEI template is 60/1,long-range ordered mesoporous structure can be obtained.With the increase of molar ratio of precursor to template,the orded structures decrease.Nitrogen adsorption results show that the specific surface area of the prepared nanoparticles can reach 198 m²/g.The doped mesoporous titanium dioxide nanoparticles have good adsorption performances for organic dyes,and have good catalytic degradation effect for organic dye MB under visible light irradiation.