Preparation And Performance Of Photothermal Conversion And Energy Stoarge Microcapsules

In order to keep the human body in a comfortable temperature for a long time,we need to control the ambient temperature of the human body in contact with the body surface within a comfortable temperature range.Phase change energy storage material is an intelligent temperature control material,when the ambient temperature is too high,it will absorb and store the heat energy in the environment to slow down the continuous rise of temperature,and when the temperature is too low,it will release the stored heat energy to achieve the positive effect of heating.However,solid-liquid phase change energy storage materials will undergo phase change during the process of use,which will inevitably lead to leakage.In order to avoid such a situation,microencapsulation technology is used as one of the core means to solve the leakage problem due to its low price,small particle size,energy saving and environmental protection features.However,the ordinary phase change energy storage microencapsulated material cannot drive itself and complete the heat storage problem in cold regions,the photothermal conversion material gives a certain thermal drive so that the phase change energy storage material can meet the demand of continuous heating for human body in extremely cold regions.Therefore,the core purpose of this thesis is to prepare photothermal energy storage microcapsules,so a series of detailed design,research and discussion are done for this purpose.The main contents include:(1)The solid-liquid phase change energy storage materials such as paraffins,fatty acids,fatty alcohols,mono esters and diesters were studied and it was found that the thermal stability of the phase change energy storage materials increased and the melting point decreased with the increase of ester groups in the molecular system for phase change energy storage materials with the same number of carbon atoms.In order to explore the influence of ester groups in phase change materials,a series of1,6-hexanediyl esters and monoesters with the same number of carbon atoms were synthesized by one-step vacuum method,and the melting temperatures of both esters were in the range of 31.4～63.7 ℃ with latent heat values greater than 200 J/g.It was found that the starting evaporation temperature of phase change energy storage materials became higher with the increase of ester groups by thermogravimetric analysis,indicating that the increase of ester groups could make the The analysis of non-isothermal crystallization kinetics shows that the increase of ester group decreases the activation energy of crystallization,which leads to the increase of the crystallization rate of phase change energy storage material;the analysis of X-ray diffraction shows that the crystal size of phase change energy storage material decreases with the increase of ester group.(2)The phase change energy storage material was microencapsulated by using polytrimethylolpropane triacrylate as the shell material to prevent leakage during use.The semi-oxidized polyaniline was successfully synthesized to enable its dispersion at the interface of micelles,and then further oxidation polymerization was carried out to prepare poly(trimethylolpropane triacrylate)/poly(aniline)composite shell material for photothermal energy storage microcapsules with a latent heat of phase change of101 J/g and a phase change temperature of 20.3 ℃.The morphology of the microcapsules was observed by electron microscopy,and it was found that the doping by semi-oxidized polyaniline would not destroy or change the spherical morphology of the microcapsules excessively;the doping by semi-oxidized polyaniline would not reduce the latent heat value of the microcapsules and the encapsulation rate of the phase change energy storage material by differential scanning calorimetry.The absorbance of the microcapsules in the near-UV to near-IR was greatly improved by the doping of polyaniline in the shell layer of the microcapsules by UV spectrophotometer analysis.Finally,the practical performance of the microcapsules for continuous heating of the human body in a sunny low temperature environment was tested by printing the microcapsules onto cotton clothes.(3)Stabilized Pickering emulsions were prepared by poly(p-phenylenediamine)instead of conventional surfactants,and a composite shell microcapsule of poly(p-phenylenediamine)was synthesized using a mimosa resin as a shell layer.In this microcapsule,poly-p-phenylenediamine was used not only as a Pickering emulsion stabilizer but also as a photo-thermal conversion material.The successful preparation of Pickering emulsion was confirmed by optical microscopy and electron scanning microscopy,and the microcapsules were tested by differential scanning calorimetry and xenon lamp simulating sunlight with latent heat of phase change up to 180 J/g and photothermal conversion efficiency up to 82.4%,and it was found that the microcapsules prepared by using poly(p-phenylenediamine)as Pickering stabilizer were more efficient than those prepared by using conventional emulsifier in(2).Although there is a small decrease in the photothermal conversion efficiency,there is a significant increase in the latent heat value and encapsulation rate.Finally,the poly(p-phenylenediamine)microcapsules were attached to cotton fabric in a printed manner for sunlight irradiation experiments to investigate their practical properties.