Preparation And Diversified Applications Of Multilayer Phase Change Microcapsules Based On Polyaniline/ZnO Nanoparticles

Solid-liquid phase change materials,characterized by high energy storage density,small volume,and stable chemical properties,are a class of reusable thermal energy storage and temperature control materials.However,it has the defects of easy leakage and poor thermal conductivity.Using microcapsule coating technology to coat phase change materials can not only prevent their leakage,but also achieve the application of phase change materials in specific fields through the design of shell materials.In this thesis,based on the diverse applications of phase change materials,multilayer phase change microcapsules coated with polyaniline/zinc oxide nanoparticles were prepared.Using the thermal temperature regulation of phase change materials,as well as the excellent electrical conductivity and photothermal absorption and conversion capabilities of polyaniline/zinc oxide composite shells,their applications in the fields of biological enzyme sensors,photothermal conversion,and thermal infrared stealth were studied.Firstly,in order to enhance the biosensor detection of histamine in foods at high temperatures,a temperature regulated biosensor based on phase change microcapsules immobilized diamine oxidase was developed.Due to the fact that biological enzymes can reduce or even inactivate their activity under high or low temperature conditions,the optimal temperature for enzyme detection should be selected.Therefore,in this experiment,based on the optimal activity temperature of diamine oxidase,n-docosane was selected as the phase change core material,and a multi-layer phase change microcapsule with titanium dioxide as the inner shell material and electrically active polyaniline/zinc oxide nanoparticles as the outer composite shell material was constructed.The dense titanium dioxide in the inner layer can effectively prevent the leakage of phase change core materials;The outer composite shell material provides a good electrical conductivity of the microcapsule.Using glutaraldehyde as a crosslinking agent,diamine oxidase was immobilized on the surface of polyaniline by covalent binding.The results showed that the latent heat capacity of immobilized enzyme phase change microcapsules exceeded 112 J/g,exhibiting good latent heat storage and release performance and thermal cycle stability.The diamine oxidase biosensor prepared using this microcapsule has achieved good thermoregulation under the reversible phase transition of n-docosane.At room temperature,the response sensitivity of the biological enzyme sensor can be as high as 52.38μA?m M^-1?cm^-2,and the detection line is 0.258μmol/L;When the ambient temperature is 50°C,compared to the biosensor without phase change core material,the biosensor exhibits a higher response sensitivity(28.57μA?m M^-1?cm^-2),with a detection limit of 0.473μmol/L.The intelligent biological enzyme sensor developed in this experiment not only has high sensitivity,but also has a wider temperature range for the determination of histamine in food.Secondly,using the thermal temperature regulation of phase change materials and the excellent photothermal absorption and conversion capabilities of polyaniline,a flexible polyurethane composite film modified by polyaniline multi-level phase change microcapsules for photothermal conversion and infrared stealth was developed.The results show that the latent enthalpy of the multilayer phase change microcapsules reaches 125 J/g,which has good thermal regulation performance.After compounding microcapsules with polyurethane,the resulting flexible composite film exhibits a good thermal insulation effect;It can also utilize the thermal temperature control ability of phase change materials to effectively reduce the surface temperature of the target object,delay the thermal response time,and achieve infrared stealth and thermal camouflage.Moreover,the excellent photothermal absorption and conversion ability of polyaniline shell ensures that the composite film can quickly convert solar energy into heat energy,improving the photothermal conversion efficiency.In addition,the composite film also exhibits a certain degree of flexibility and hydrophobic self-cleaning effect,which has great application prospects in flexible composite fields such as infrared stealth and thermal camouflage.