Microencapsulated N-docosane Phase Change Material With Reversible Thermochromic Characteristics

Reversible thermochromic composite is a intelligent material,which can change its color responding thermally to the environmental temperature.And in particular,its color changes are usually caused by the phase shift due to the temperature change.Functional materials make up more than 85%in the field of new materials,which occupy the hot spots of innovative and high technology.Such a composite has characterized by poor environmentally stability,weak abilities of anti-disturbance,which means it can’t realize cyclic thermochromic characteristics obviously and reversibly in practical application.To solve the above problems,it needs to be microcapsulated by PMMA.In this study,we discussed systematically the encapsulation,characterization and application of TC-MPCMs.The TC-composite is coated by PMMA and then immobilized on the surface of phase change microcapsules,which has the function of thermal energy storage and reversible thermochromic characteristics.As a result,microcapsules with reversible thermochromic characteristics can show intuitively the internal status of phase change materials which is storing or releasing energy.In this paper,we fabricate the microPCMs with SiO2 shell in the oil-in-water(O/W)system by the emulsion polymerization method,using MPTMS as surface treating agent to immobilize the reversible thermochromic composite.The influence on microstructure,the melting and crystallization properties,thermal energy storage properties,heat stability,as well as reversible thermochromic characteristics of TC-MPCMs are discussed via scanning electron microscope(FE-SEM),transmission electron microscope(TEM),different scanning calorimetry(DSC),and thermogravimetric analysis(TGA).Furthermore,the chemical structure is investigated by using X-ray photoelectron spectroscopy(XPS),X-ray diffraction spectroscopy(XRD)and Fourier infrared spectroscopy(FT-IR).In addition,the reversible thermochromic characteristics of TC-MPCMs was carried out via cyclic heating and cooling stage.Thermal energy storage analysis test showed that the melting enthalpy of TC-MPCMs is 125.5 J/g,and the crystallization enthalpy is 121.1J/g.Compared with reversible thermochromic composite,TC-MPCMs has a good morphological stability and the reversible thermochromism characteristics.Through characterizing the temperature of discoloration and phase transition,it has shown that the thermochromic composite can express effectively the internal state of phase change material which is storing or releasing energy.storage of nuclear material or color changes can release status.In conclusion,these results suggested that TC-MPCMs exhibited good reversible thermochromic performance,cyclic stability,morphological stability,environmental tolerance and matching temperature of indicating.These dual functionalized microcapsules can be a great potential candidate for early warning and protection in various emerging applications of solar cells,thermo-sensors,architectural coatings,food and medicine package and some exothermic reactions,in addition to traditional thermal energy storage...