Construction And Function Of Three-Dimensional Micro-Nano Hierarchically Porous Heterogeneous Phase Change Material Composites

Currently,organic phase change materials(mainly solid-liquid phase change materials)mainly have the disadvantages of easy leakage in liquid state,low thermal conductivity and single function,which greatly limit their widespread application.Developing shape-stabilized composite phase change materials can not only effectively prevent the leakage of during the solid-liquid phase transition process,but also improve the comprehensive performances of organic phase change materials.Hence,the development of high-performance shape-stabilized composite phase change materials has become the focus and hotspot of research in the field of phase change energy storage.Based on the size effect and pore characteristics of micro-nano hierarchically porous carbon and metal-organic framework materials,we systematically studied the nanoconfinement effect of organic phase change materials in the confined hierarchical channels,developed composite phase change materials with synergistic enhancement of thermal energy storage and transfer,and developed multifunctional composite phase change materials with photoluminescence and thermotherapy functions.This provides theoretical and experimental basis for the controllable construction,functional integration and application of micro-nano porous materials in the field of thermal energy storage.The specific research contents are as follows:(1)The carbonization mechanism was clarified,and the pore sizes and surface properties of in-situ nitrogen-doped hierarchically porous carbon were controlled by adjusting the calcination temperature of polyaniline gel.Combined with density functional theory,the nanoconfinement mechanism of organic phase change materials with different functional groups and different numbers of carbon atoms in the restricted nitrogen-doped hierarchically porous carbon is revealed,which mainly depends on the hydrogen bond strength and spatial size limitation between organic phase change materials and nitrogen-doped hierarchically porous carbon.It provides the theoretical basis for the development of carbon-based organic composite phase change materials with excellent comprehensive performances.(2)The way to directly enhance the thermal conductivity of the supporting material is utilized.Highly thermally conductive three-dimensional micro-nano porous network carbon material was constructed through high-temperature calcination of carbon quantum dots.The chemical regulation reaction mechanism is clarified by adjusting the calcination temperature and cross-linking reaction.The regulated three-dimensional and high graphitization network carbon material optimize the phonon heat transfer channels,thus obtaining the synergistic enhancement of the thermal energy storage and transfer capacity of organic composite phase change materials.The thermal energy storage and transfer mechanism of organic composite phase change materials is clarified,which provides the theoretical and experimental basis for the development of carbon-based organic composite phase change materials with excellent comprehensive performances.(3)Metal-organic framework serves as porous host,carbon quantum dots and organic phase change materials serve as functional objects,and a novel type of MOF-based composite phase change materials with photoluminescence function is constructed to realize thermal energy storage and photoluminescence emission.Based on the functional units of carbon nanotube sponge,thermotherapy mask with dual functions of air purification and temperature regulation was designed,which shows superior thermotherapy for allergic rhinitis and great application potential in the field of biomedicine.This synergistic integration strategy of different functional unit materials provides an innovative platform for the design and development of advanced novel multifunctional composite phase change materials.