Preparation Of Conjugated Microporous Polymer Microspheres And Study On Solar Photothermal Conversion Properties Of Composite Phase Change Materials

Solar energy is a clean energy,new energy,with easy access,sustainable,non-depleting and other characteristics,is the main direction of the world’s energy development layout,but also to achieve the"carbon peak,carbon neutral"one of the major national strategic objectives of priority development areas.The development of solar thermal conversion materials with high performance and high energy density is an important research direction for solar energy utilization.Conjugated microporous polymers（CMPs）are a typical class of organic porous materials with permanent micro-and nano-pore structures,and are prepared by various methods and have stable physicochemical properties.In particular,the structure and composition of CMPs can be controlled by the"bottom-to-up"synthesis strategy,which provides unlimited possibilities and new research ideas for the design of new photothermal conversion materials.Based on this,this paper synthesizes a series of CMPs hollow microspheres with different structures and chemical compositions of alkynyl aromatic compounds and halogenated aromatic compounds as monomers,and prepares composite phase change materials with high energy density and high photothermal conversion efficiency and not easy to leak with the help of their unique cavity structures,and systematically studies their applications in solar photothermal conversion to realize the efficient and clean utilization of solar energy.At the same time,it also provides new ideas for the research of efficient utilization of solar energy.The main research contents of this paper include:In the second chapter of this paper,hollow microspheres of CMPs with different structures were synthesized by Sonogashira-Hagihara cross-coupling reaction using trichloroisocyanuric acid and 1,3,5-triethynylbenzene and 1,4-diethynylbenzene as monomers,toluene and triethylamine as solvents,cuprous iodide and tetrakis（triphenylphosphine）palladium（0）as catalysts,and SiO₂ microspheres as hard templates（CMPs-HS）.The microsphere diameters of the two CMPs-HS were about 700 nm,and the BET specific surface areas were 519.95 m² g^-1 and 309.26 m²g^-1,respectively.two CMPs-based composite phase change materials（GCMPs@ODA）were prepared by compounding the CMPs-HS surface modified by graphene coating（GCMPs-HS）with organic phase change materials（PCMs）.The porous structure and special cavities of CMPs-HS create excellent conditions for loading PCMs,resulting in the excellent thermal storage capacity of GCMPs@ODA,with the latent heat of phase change of 217.4 J g^-1 and 224.6 J g^-1,respectively,and the enthalpy of phase change does not decrease significantly after several cycles.In photothermal conversion applications,GCMPs@ODA The solar thermal conversion efficiency can reach 87.15%and 85.83%respectively,which has potential application value in solar energy storage and conversion.On the basis of the above,in Chapter 3 of this article,hollow microspheres of CMPs（CMPHS）were prepared using 1,3,5-triaethynylbenzene and2,4,6-tribromoaniline as reaction monomers through Sonogashira-Hagihara cross coupling reaction combined with template method.After high-temperature pyrolysis（CCMPHS）,three types of CMP based phase change composites were prepared by combining them with fatty alcohol based phase change materials（CCMP@PCMs）。Pyrolysis at high temperature makes CCMPHS have excellent light absorption ability（absorption rate>80%）The photothermal conversion efficiency of the CCMP@PCMs reached 86.83%,89.45%,and 85.40%,respectively.Pass the DSC test,The latent enthalpies of CCMPHS@PCMs reached 220.1 J g^-1,244.6 J g^-1,and 228.8 J g^-1,respectively.After 50 and 100 endothermic and exothermic cycles,the phase change enthalpy does not change significantly,and there is no leakage of phase change materials.In addition,for CCMPHS@PCMs Conducting electrothermal conversion experiments,it was found that the electrothermal conversion efficiency of composite phase change materials was 83.81%,81.10%,and 90.50%,respectively.The above research results indicate that,CCMPHS@PCMs is expected to become an ideal candidate for new solar energy storage and conversion materials.The above research results indicate that,CCMPHS@PCMs It is expected to become an ideal candidate for new solar energy storage and conversion materials.