Controllable Construction Of Mesoporous Nanomaterials Based On Interfacial Polymerization And Assembly

Mesoporous materials have attracted extensive attentions because of their intrinsic characteristics such as high specific surface area,large pore volume,adjustable pore size and diversified pore structure.Mesoporous materials tend to have micron size,which limits their further application.Mesoporous nanomaterials possess the specific advantages of mesoporous materials and the inherent characteristics of nanomaterials,thus they have great application potential in the fields of catalysis,energy storage and energy conversion,adsorption and separation,drug loading and release.In the past two decades,with the improvement of science and technology,a variety of low-dimensional mesoporous nanomaterials including zero-dimensional mesoporous nanomaterials,one-dimensional mesoporous nanomaterials and two-dimensional mesoporous nanomaterials have been successfully synthesized and constructed,which greatly enriched the types and applications of mesoporous nanomaterials.However,there are still some important problems to be solved urgently in the design and synthesis of mesoporous nanomaterials:（1）Ordered mesoporous carbon synthesized by traditional methods usually has a three-dimensional structure.The unsatisfactory electrical conductivity and bulk structure of ordered mesoporous carbon materials limit its further application in electrochemical field;（2）Current porous polymers synthesized by hard template method and PS-b-PEO copolymers self-assembly method mostly have the pore structure of spherical mesopore.The adjustment of pore structure of mesoporous polymers by soft template method is still a great challenge;（3）The synthesis of mesoporous polymers often relies on non-commercial diblock copolymers as templates,which not only makes the pore structure and morphology of mesoporous polymers difficult to be accurately controlled,but also limits the large-scale production and application of mesoporous polymers.These existing problems limit the further application of mesoporous nanomaterials.Therefore,it is very necessary to develop new synthesis strategies to accurately control the morphology and fine structure of mesoporous nanomaterials.In this paper,the precise assembly of ordered mesoporous carbon materials and mesoporous polymer materials was realized on the two-dimensional interface.The fine controllable synthesis of porous conductive polymer nanomaterials was realized by using the droplet template method.The influences of pore structure,specific surface area,composition,morphology and other factors on the electrochemical performance of mesoporous materials were systematically explored.In the second chapter,we developed an interface-induced self-assembly strategy to synthesize sandwich-like ordered mesoporous carbon/Ti₃C₂T_x heterostructures（OMCTs）.In this strategy,Pluronic F127 was used as template to self-assemble with low molecular weight phenolic resin,and stable F127/phenolic resin spherical single micelles were formed in dilute aqueous solution.After Ti₃C₂T_x was introduced into the synthesis system,the hydroxyl group（-OH）of F127/resol spherical complex was hydrogen-bonded with the surface functional groups（-OH and-F）of Ti₃C₂T_x,and grew evenly on both sides of the interface of Ti₃C₂T_x to prevent the accumulation of Ti₃C₂T_xnanosheets.During the carbonization process,the resin network can be converted into ordered mesoporous carbon in situ,which can prevent the oxidation of Ti₃C₂T_xnanosheets at high temperatures（up to 600℃）,thus ensuring the thermodynamic stability of OMCT.The porous structure of OMCT can be easily adjusted by adjusting the mass ratio of F127/resol complex micelles to Ti₃C₂T_x.The prepared OMCT has ordered mesoporous structure,high specific surface area(259～544 m² g^-1)and large pore volume(0.296～0.481 cm³ g^-1).Benefiting from these advantages,OMCT exhibits excellent ultracapacitor performance when used as an ultracapacitor electrode material,including excellent specific capacitance of 247 F g^-1 at 0.2 A g^-1,satisfactory rate capability of 190 F g^-1at 5 A g^-1 and excellent cycling performance.In the third chapter,we developed a swelling-induced structural transformation strategy to construct 2D porous polypyrrole/MXene heterostructures（2D porous PPy/MXene）by using Pluronic P123 as only template,1,3,5-trimethylbenzene（TMB）as swelling agent and MXene nanosheets（Ti₃C₂T_x）as 2D substrate.By adjusting the dosages of TMB,the hydrodynamic diameters of the composite micelles formed by self-assembly P123 and TMB can be regulated from 11.7 to 58.7 nm,thus achieving the precise control over pore structures（cylindrical mesostructure,spherical mesostructure and spherical macrostructure）,pore sizes（7.8～52.0 nm）and specific surface area(129～188 m² g^-1)of 2D porous PPy/MXene.Due to the cylindrical mesoporous structure providing a fast electrolyte transferring mode,large electrolyte/electrode contact area and shorter ion diffusion distance,the obtained 2D cylindrical mesoporous PPy/MXene exhibits the optimal supercapacitor performances,including high capacitance of 477 F g^-1 at 1 A g^-1,superior rate performance of 296 F g^-1 at 5 A g^-1 and favorable cyclability with tiny capacitance degradation（5.8%）after10 000 cycles.This work not only reveals the structure-activity relationship between pore structure and electrochemical performance,but also provides new insights for the construction of novel 2D porous heterostructure materials.In the forth chapter,we demonstrate a novel self-assembly strategy for the synthesis of porous conducting polymers（PCPs）with diverse porous structures and morphologies.In this strategy,pyrrole monomer was used as polymer precursor,Pluronic P123 as template and stabilizer,and 1,3,5-trimethylbenzene（TMB）as hydrophobic interaction mediator.In the reaction process,P123 not only acts as a structural guide agent to stabilize the oil droplet template,but also acts as a stabilizer to adsorb on the surface of polypyrrole,so as to reduce the surface energy,respectively induce the formation of various porous structures and regulate the product morphology.Tunable spherical composite micelles can be used as different building blocks to construct different types of PCPs.Five kinds of PCPs with different porous structures and morphology were obtained after polymerization,namely mesoporous conducting polymer nanospheres（Meso-PCP-N）and mesoporous conducting polymer blocks（Meso-PCP-x,where x is the volume ratio of TMB to P123,x=1,2,3）and macroporous conducting polymer（denoted as Macro-PCP）.In addition,the morphology and pore structure of the product can be easily adjusted by changing the dosage of P123 and TMB and the concentration of the polymer precursor.The diameter of Meso-PCP-N can be adjusted from 70 nm to 140 nm,and the aperture of PCP can be adjusted from 7nm to 100 nm.The prepared PCPs have the characteristics of controllable porous structure（mesoporous structure,macroporous structure）,uniform pore size,high specific surface area(132～222 m² g^-1)and large pore volume.Because of these excellent properties,PCPs,as the anode material of sodium ion battery,exhibit very high reversible performance,excellent multiplier performance and excellent cycling performance.