Latent heat thermal energy storage based on phase change materials (PCM) is considered to be an effective method to solve the contradiction between solar energy supply and demand in time and space. The development of PCM composites with high solar energy absorption efficiency and high energy storage density is the key to solar thermal storage technology. In this paper, a green and simple method is proposed to fabricate a porous PCM with stable shape, low supercooling degree and excellent photo-thermal conversion performance. The novel PCM which combine porous expanded graphite as the carrier material, n-eicosane as the stabilizer and sodium acetate trihydrate (SAT) as phase change energy storage material are designed and prepared by melt blending method. The expanded graphite contributes to the stable shape of the composites, and provides excellent thermal conductivity channels and light absorption properties as well. The composite PCM sample containing 3.3 wt% expanded graphite achieves excellent performance, phase change enthalpy of 266.54 J/g and a photothermal conversion efficiency of 91.14 %, and shows low supercooling degree of 2.2 °C with almost no leakage at 90 °C.
Xiaolan Chen,Naiding Zhang,Chujun Ni,Ruijue Cao,Lanting Hu,Jinyi Chen,Qian Zhao,Tao Xie,Zhenjie Liu
Porous shape memory polymers (SMPs) can execute large volume expansion from their compressed temporary shapes to porous permanent shapes, which present promising practical potentials in biomedical and aerospace fields. While constructing sophisticated geometries are essential for achieving the corresponding functions of the foams, the original shapes which are typically determined by molds cannot be post-tuned in a customized fashion. Here we propose an easy but effective emulsion lyophilization method to fabricate porous SMPs, the original shapes of which can be post-regulated via a two-stage curing mechanism. A thermo-curable acrylate emulsion and a photo-curable polyurethane emulsion were prepared individually and then mixed in proportion. After lyophilization of the mixed emulsion, porous SMPs were prepared due to the first thermo-curing stage between epoxy and amine groups from the acrylate emulsion. The foams can be temporarily programmed into alternative shapes with relatively complex geometries which can afterwards be permanently fixed through the secondary photo-curing stage. In this way, simple permanent shapes of the porous SMPs determined by planar molds were converted into customized three-dimensional ones taking advantage of various deformation such as bending, imprinting, and twisting. Accordingly, customized biomedical devices were fabricated via the two-stage curing process, inspiring further application opportunities for porous SMPs.
Zhenliang Zhu,Bei Li,Xing Liu,Peixin Zhang,Shixia Chen,Qiang Deng,Zheling Zeng,Jun Wang,Shuguang Deng
Adsorptive separation of xenon (Xe) from krypton (Kr) is challenging owing to their low concentrations and similar physical properties. Herein, we report two metal–organic frameworks (MOFs) assembled from the same aliphatic ligand ( trans -1, 4-cyclohexanedicarboxylic acid, H 2 CDC), but showing distinct pore shapes. The rhombus pores on Al-CDC show a narrower pore aperture of 4.5 Å × 6.0 Å, contracting to the pseudo-square pores (5.8 Å × 6.8 Å) on Cu-CDC. As a result, Al-CDC exhibits a high Xe adsorption capacity (2.45 mmol g −1 ) and Xe/Kr selectivity (10.7) at 298 K and 1.0 bar. The confined pore space and abundant saturated C-H groups provide stronger van der Waals interactions toward Xe, which is disclosed by the Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) calculations. Dynamic breakthrough experiments further confirm their industrial application potential and stable reusability.
危险品化学品经营许可证（带存储）