| pH sensitive materials belong to the intelligent materials,intelligent materials can be active to respond to changes in the surrounding,intelligent material is a lot of more phyletic,such as metal,nonmetal materials,polymer materials,photosensitive intelligent high polymer materials,pH sensitive polymer materials.The sensitive polymer is when the outside changes(such as pH,temperature),the polymer is the same as the"indicator",and the external changes are reflected in its unique form.Scientists through continuous experiment found that sensitive materials can be applied to the release of drug and protein separation,the future will be promising in study of drug controlled release and biological treatment.Polymethacrylic acid(PMAA)monomers are methacrylic acid,a material widely used in environmental sensitive areas,especially in terms of pH sensitivity.Poly(methyl methacrylate acrylic monomers of alpha,the solvability of the molecular structure of the carboxyl is from carboxyl,when pH change around,carboxyl can get or lose a proton,surroundings and acidic carboxyl in non dissociation-COOH,can form hydrogen bonds between adjacent of carboxyl makes alpha methyl acrylic acid is contracting;When the pH value increases,the carboxyl group releases the proton dissociation-COO-and loses the hydrogen bond.ynthetic part of this thesis experiment,is was eicosane as core material phase change material,with the aid of methyl methacrylate(MMA),thermal conductivity and stability,and methylacrylic acid(MAA),hydroxyl,the characteristic of pH sensitive to both polymer as the outer layer of the microcapsule wall material,implementation of copolymer is eicosane core material coated,will is eicosane microcapsules.Experimental process using monomer methylacrylic acid armour grease and methyl acrylic acid,surfactant sodium dodecyl sulfate,the initiator two benzoyl peroxide,azodiisobutyronitrile,potassium persulfate.The effects of the concentration of surfactant,different stirring rate,n-octane and monomer on the surface morphology,microstructure and phase change of microcapsules were studied.In this paper,the scanning electron microscope(SEM)is used to observe the surface morphology of microcapsules.Transmission microscope is the microstructure of microencapsulation microencapsulation.X-ray energy spectrum analysis(EDAX)can further analyze the composition and content of elements of microcapsules.X-ray photoelectron spectroscopy(XPS)can analyze the chemical elements of microcapsules.Differential scanning calorimeter(DSC)and thermogravimetric analysis(TGA)can directly demonstrate the surface capability,durability and thermal stability of microcapsules.The photothermal conversion efficiency of solar energy of microcapsule was analyzed by infrared thermal imager.NMR is used to test the structure of copolymer and the link of structural units.Preparation of poly(methyl methacrylate and methyl acrylic coating are eicosane microcapsule is the best synthesis condition of the surfactant concentration is 0.2 mol.L-1,stirring speed of 350 r/min,and under the condition of the synthesis of the microcapsule has good core-shell structure,microstructure of microcapsules for the smooth surface of the sphere.Under the condition of the best synthetic phase change of the preparation of microcapsule has good performance,thermal stability,durability,resistance to permeability,can better realize the solar-thermal nd poly(methyl acrylic acid copolymer of cladding eicosane to have the dual functional,out with the storage temperature adjustment function of phase change materials is eicosane,hold concurrently at the same time also pH sensitivity. |
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