Preparation and properties of phase change capsules with aminated dense silica shell layers
Phase change nanocapsules(NEPCM)with n-octadecane(C18)phase change material as the core ma-terial and silica(SiO2)as the shell material were prepared by sol-gel method.A silane coupling agent,3-Amin-opropyltriethoxysilane(APTES),was added to functionalize the SiO2 surface.In addition,the addition of APTES promoted the hydrolysis and condensation of Tetraethyl orthosilicate(TEOS)to form a dense SiO2 shell layer.The effects of different core/shell mass ratios on the microscopic morphology and phase change en-thalpy of NEPCM were investigated.Meanwhile,the properties of NEPCM,such as thermal cycling stability,leakage prevention,thermal stability,and temperature regulation of the interior of the building,were also stud-ied in detail.The results showed that the phase change enthalpy of NEPCM changed with the change of core/shell mass ratio.At the core/shell mass ratio of 1/1.3,the phase change enthalpy of the prepared nanocapsules was the highest,reaching 140.57 J/g,with an encapsulation rate of 61.6％.Meanwhile,due to the protection of dense SiO2 shell material,NEPCM had good leakage prevention compared with pure Ci8.Its enthalpy only de-creased by 0.13％after 150 heating-cooling cycles,which exhibited excellent thermal cycle stability and durabil-ity.In addition,when NEPCM was used in building thermal management,it effectively delayed the time for the indoor temperature to reach the peak temperature by 385 s and reduced the peak temperature by 9 ℃,which in-dicated that NEPCM had excellent thermal storage and thermoregulation performance.Meanwhile,the addition of APTES functionalized the NEPCM shell,and the efficient interactions between the surface amino groups and the functional groups of the organic polymer provided a broad application prospect for the efficient preparation of nanocomposites.
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