RESUMEN
Multifunctional phase change materials (PCMs) are highly desirable for the thermal management of miniaturized and integrated electronic devices. However, the development of flexible PCMs possessing heat energy storage, shape memory, and adjustable electromagnetic interference (EMI) shielding properties under complex conditions remains a challenge. Herein, the multifunctional PCM composites were prepared by encapsulating poly(ethylene glycol) (PEG) into porous MXene/silver nanowire (AgNW) hybrid sponges by vacuum impregnation. Melamine foams (MFs) were chosen as a template to coat with MXene/AgNW (MA) to construct a continuous electrical/thermal conductive network. The MF@MA/PEG composites showed a high latent heat (141.3 J/g), high dimension retention ratio (96.8%), good electrical conductivity (75.3 S/m), and largely enhanced thermal conductivity (2.6 times of MF/PEG). Moreover, by triggering the phase change of the PEG, the sponges displayed a significant photoinduced shape memory function with a high shape fixation ratio (â¼100%) and recovery ratio (â¼100%). Interestingly, the EMI shielding effectiveness (SE) can be adjusted from 12.4 to 30.5 dB by a facile compression-recovery process based on shape memory properties. Furthermore, a finite element simulation was conducted to emphasize the advantage of the MF@MA/PEG composites in the thermal management of chips. Such flexible PCM composites with high latent heat storage, light-actuated shape memory, and adjustable EMI shielding functions exhibit great potential as smart thermal management materials in military and aerospace applications.
RESUMEN
Strong rigidity, low thermal conductivity, and short of multi-driven capabilities of form-stable phase change materials (FSPCMs) have limited their practical utilization. Herein, we report a shape-adaptable FSPCM with the coinstantaneous light/electro-driven shape memory properties and light/electro-to-thermal energy storage performance. The FSPCM is fabricated by incorporating the poly(ethylene glycol) (PEG) into the cellulose nanofiber/graphene nanoplatelet (GNP) hybrid-coated melamine foam (CG@MF). The CG@MF/PEG FSPCMs show a good encapsulation effect, enhanced thermal conductivity, and large melting enthalpy (178.9 J g-1). Due to the high elasticity of MF and the excellent photothermal conversion and electrical conductivity of the GNP network, the CG@MF/PEG FSPCMs exhibit a remarkable light/electro-driven shape memory effect by activating the phase change process of PEG. Meanwhile, the CG@MF/PEG FSPCMs can effectively convert light or electric energy into heat energy and reposit the converted energy during the phase change process. Furthermore, the CG@MF/PEG FSPCMs possess excellent multiresponsive self-adhesion properties. A light-sensitive, shape-adaptable, and thermal-insulating container is further explored. This study provides routes toward the development of multiresponsive shape-adaptable FSPCMs for energy storage applications.
RESUMEN
Paraffin wax (PW) is widely used as a phase change material (PCM) in the thermal energy storage field, whereas the leakage and strong rigidity of PW have hindered its practical applications. In this work, binary melamine foam (MF)/PW blends with simultaneous thermal energy storage and shape memory properties were prepared through vacuum impregnation. Herein, PW performs as a latent heat storage material and as a switching phase for shape fixation and MF serves as a supporting material to prevent the leakage and as a permanent phase for shape recovery. Due to the light weight and super-elasticity of MF, the MF/PW PCMs possess not only good encapsulation ability and a high latent heat, but also excellent shape-fixing and recovery properties (shape-fixing and recovery ratios are about 100%). Besides, the MF/PW PCMs can be fabricated into arbitrary shapes using MF as a template, and they exhibit excellent shape memory cyclic performance and thermal reliability. A temperature-sensitive and temperature-controlled deployable panel is further established, which can be installed in the electronic device and used for temperature protection. With high thermal energy storage capability, excellent shape memory properties, shape designability, and stable cycling reliability, this multifunctional MF/PW PCM shows a promising application in thermal energy management systems.