Research progress in microcapsules of phase change materials
Significance Influenced by global energy crisis in the 1970s,improvement of energy efficiency and identification of alternative sustainable energy have become an urgent need of the moprden society.Along with this,the research and application of microcapsules of phase change materials(PCMs)have attracted much attention.Microcapsules of PCMs are a type of core-shell structured micro/nano smart materials.The core materials are the phase change materials and the shell materials are organic or inorganic substances.Encapsulation technology for phase change materials can facilitate the maintenance of shape in solid-liquid PCMs and can overcome phase segregation and low thermal conductivity.It effectively overcomes defects such as volume changes,leakage,and supercooling that occur during solid-liquid phase transitions of phase change materials.As a result,it significantly reduces the"phase separation"phenomenon and improves the stability of phase change materials.Owing to their unique advantages in energy storage and temperature regulation,microcapsules of PCMs have been widely applied in various fields such as textiles,medical care,architecture and solar energy.Therefore,the exploration of their preparation techniques and applications presents important scientific significance and research value.Progress The clarification of the commonly used core and shell materials,the preparation technologies of microcapsules of PCMs and their applications were comprehensively reviewed.The microcapsules of PCMs consist of a core material,which is the phase change material itself,encapsulated within the microcapsule,a shell material used to protect the core material from leakage.The shell material should possess certain mechanical strength,compactness,and should not react chemically with the core materials.The preparation techniques for PCM microcapsules mainly include physical methods,chemical methods,and physicochemical methods.Physical methods are those in which the encapsulation of PCMs uses only physical processes such as drying and bonding,where the materials forming the shell do not undergo any chemical reactions with the core materials.The obtained microcapsules of PCMs exhibit good stability and controllability,and are suitable for micro-scale systems.For the chemical methods,the shell of microcapsules is synthesized through polymerization or condensation reactions between monomers,oligomers,or pre-polymers at the oil-water interface.Microcapsules of PCMs prepared by chemical methods have excellent performance and small particle sizes and simple operation.Physicochemical methods are a technique that combines physical methods such as heating and cooling with chemical methods such as hydrolysis,crosslinking and polycondensation.Microcapsules of PCMs with different characteristics and functions such as enhanced stability,small particle size and improved controllability can be prepared by adopting different preparation methods.Therefore,PCMs are widely used in textiles,medical care,architecture,solar energy,and other fields.Conclusion and Prospect PCM Microcapsules have broad applications.There are still some challenges and problems in practical production.Firstly,the high cost of phase change materials limits their widespread applications due to the expensive production process.Secondly,the material loss is quite high in the preparation of PCM microcapsules.In order to the above problems,the preparation process of microcapsules of PCMs can be improved or replaced by a more economical and efficient production mode.Meanwhile,how to improve the coating rate of microcapsules and increase the response speed are also the current research and development directions of PCM microcapsules.Finally,it is conducive to the promotion of development of the microcapsules of PCMs to green and multi-functional directions by combining the properties of heat storage and temperature regulation with the environmentally friendly multi-functional materials.It can also contribute to the reduction of energy consumption and the enhancement of energy utilization efficiency,which would benefit human beings and the environment.
万方数据
维普
