Li Feng,Shunping Dong,He Zhou,Lijun Yang,Fen Yuan,Yibin Yang,Jingxin Lei,Lixia Bao,Longchun Bian,Jiliang Wang
It is still a big challenge to obtain shape-stabilized nanoencapsulated core-shell phase change materials (NC-PCMs) with the encapsulation ratio up to 90 wt% via surfactant-free method due to the lack of novel nanoencapsulation method and related mechanism. Herein, we for the first time report a novel supramolecular lock shell layer technique without surfactant to facilely prepare shape-stabilized NC-PCMs with the encapsulation ratio range of 70–90 wt%. To this aim, amphiphilic macromolecular nanoreactors with the particle size of ~15 nm were firstly synthesized. n-Dodecanol as the heat storage core was then self-assembled into the nanoreactors under ultrasonification. A thin layer of crosslinked acrylates copolymers was prepared by in-situ grafting polymerization to further stabilize the potentially leaked n-dodecanol. Crystalline structure, morphology, and thermal behavior of the resulting NC-PCMs were extensively investigated. Relevant results indicate that the obtained NC-PCMs fluids show excellent storage stability in the temperature range of −50 to 50 °C, benefiting from their small particle size (60–90 nm) and intense supramolecular interactions between n-dodecanol and the prepared nanoreactors. Phase change temperature of the produced NC-PCMs is very close to that of neat n-dodecanol, no obvious supercooling phenomena have been detected for the produced NC-PCMs. The maximum encapsulation ratio, latent heat, and thermal conductivity of the shape-stabilized NC-PCMs approximate 90 wt%, 180 J g −1 , and 0.1705 W m −1 K −1 , respectively, implying large potential application in the sectors of solar energy storage, waste heat management etc. The developed supramolecular lock-layer technique probably opens a new avenue in the search for NC-PCMs with ultrahigh mass content of core layer.
Lixia Geng,Shuangfeng Wang,Tingyu Wang,Ruilian Luo
A novel nanencapsulated phase change material (NEPCM) was fabricated via the self-assembly method with n-dodecanol as the core and SiO2 derived from sodium silicate as the shell. The as-prepared nanocapsules with different core/shell ratios were investigated systematically. Scanning electron microscopy and transmission electron microscopy photographs indicated that the products had a nearly spherical and compact surface with nanometer size. Fourier transform infrared spectroscopy and X-ray diffraction confirmed that SiO2 was successfully encapsulated upon n-dodecanol. Differential scanning calorimetry results showed that the NEPCMs exhibited similar phase change characteristics to pristine n-dodecanol, which melted at 21.03 °C with a latent heat of 116.7 J/g and solidified at 19.58 °C with a latent heat of 114.6 J/g. Thermogravimetric analysis and thermal cycle tests revealed that the nanocapsules had good thermal stability. In conclusion, the prepared nanocapsules have great potential for thermal energy storage and building energy conservation as a result of their facile synthesis process, low cost, and excellent thermal properties.
Nontoxic, low-cost microcapsule phase change materials (MicroPCMs) were successfully manufactured via suspension polymerization, in which n-dodecanol was employed as the core material and crosslinked polymethyl methacrylate as the wall material. Alkylphenol polyoxyethylene ether (OP-10), polysorbate-20 (Tween-20), sodium salt of styrene-maleic anhydride polymer (SMA), sodium dodecyl sulfonate (SDS), and hexadecyltrimethylammonium chloride (1631) were employed as emulsifiers to investigate the effects of the type and amount of emulsifier on MicroPCMs. In addition, the effects of different types of crosslinking agents on the fabrication of MicroPCMs were investigated. Scanning electron microscopy was used to observe the micro-morphology of MicroPCMs. The chemical structure of the MicroPCMs was detected via Fourier transform infrared spectroscopy. The thermal properties and thermal stability of the MicroPCMs were analyzed using a differential scanning calorimeter and a thermal gravimetric analyzer, respectively. Particle size distributions of the MicroPCMs were measured using a particle size analyzer. The results demonstrate that MicroPCMs with regular morphology were prepared when the mass ratio of the SMA to the oil phase was 3%, and the latent heat and yield of the MicroPCMs were 80.29 J g−1 and 84%, respectively. Furthermore, the MicroPCMs were successfully synthesized using pentaerythritol triacrylate containing the hydroxyl group as the crosslinking agent with an average particle size of 14.18 μm and excellent thermal stability.
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