Study On The Synthesis And Properties Of The Conjugated Microporous Polymers Nanotubes Aerogels

Conjugated microporous polymers are a kind of organic porous polymer materials with three-dimensional network structure and composed by the light elements such as C?H and N etc,which are widely used in the fields of gas storage,separation,catalysis,separation of organic pollutants,energy storage and conversion because of their simple and diverse preparation methods,high specific surface area,adjustable structure,morphology and high physical and chemical stability.Traditionally,the conjugated microporous polymers obtained by Pd(0)/Cu I catalyzed Sonogashira-hagihara cross-coupling reaction are amorphous powdery materials due to its irreversibility in thermodynamics.Their insoluble and melt properties make it difficult to prepare bulk or thin film materials by post-processing.In recent years,although there reports the preparation of the conjugated microporous polymer monolithic materials,they always suffer from the poor mechanical properties,which limits their practical applications.Therefore,the fabrication of the monolithic conjugated microporous polymer materials with high mechanical strength is still a challenge.Based on this,a series of conjugated microporous polymer aerogels materials were prepared through the selection of monomers with different activity,molecular structure and strictly controlling of the sol-gel phase transformation process.The formation mechanism of the conjugated microporous polymer aerogels is preliminarily discussed and the energy storage and solar photothermal conversion performance of these conjugated microporous polymers were also investigated.The main contents and conclusions of this paper are as follows:(1)Three kinds of conjugated microporous polymers monolithic foams CMP-MN0,CMP-MN1 and CMP-MN2 were prepared by using 2,4,6-tribromoaniline and 1,3,5-triethynylbenzene as monomers with the molar ratio of acetylene and bromine in monomers fixed at 1:1 1.5:1 and 2:1 respectively.Among them,CMP-MN0 is composed by spherical and nanotube mixed monolithic material with loose structure and poor mechanical strength.In contrast,CMP-MN1 and CMP-MN2 are monolithic materials with high mechanical strength and composed by nanotubular structure.BET specific surface area was found to be 37 m2 g-1 for CMP-MN1 and 170m2 g-1 for CMP-MN2,respectively.The compressive strength was calculated to be0.76 MPa for CMP-MN1 and 1.52 MPa for CMP-MN2 respectively,under 75% strain,which is the highest reported value among the CMPs monolothic materials.Based on the unique superoleophilic nature and porous tubular structure of the CMP-MNs,theCMP-MNs/Paraffin composite phase change materials were prepared by melt impregnation method and the CMP-MNs/Paraffin composite phase change materials show excellent thermal storage properties and stability.(2)Conjugated microporous polymers aerogels,CMPA-1 and CMPA-2 were prepared by reaction of 1,3,5-triethynylbenzene with 1,4-dibromobenzene and4,4'-dibromobiphenyl,respectively,with the molar ratio of acetylene and bromine in monomers fixed at 2:1.The BET specific surface areas were calculated to be 430 m2g-1 for CMPA-1 and 181 m2 g-1 for CMPA-2.The compressive strength was found to be 0.5 MPa for CMPA-1 and 0.54 MPa for CMPA-2 respectively under 75% strain.After one-step oxidation,CMPAs material was transformed into hydrophilic CMPAs for the first time.Based on CMPAs nanotubular porous structure,low thermal conductivity and fast water molecule transport,we first report the application of CMPAs as a photothermal conversion material for solar steam generation.After coated the carbon black on the surface of CMPAs,the CMPAs carbon black composite materials can reach an energy conversion efficiency of 81% under 1 kW m-2 solar irradiation.(3)A tubular conjugated microporous polymer aerogel was prepared by the reaction of 2-amino-3,5-dibromide pyridine and 1,3,5-triethynylbenzene.The porosity of the PCMPAs was calculated to be 94%.The compressive strength of PCMPAs was measured to be 0.54 MPa under 75% strain.After coated with PPy,the PCMPAs-PPy exhibit high optical absorption properties.As a photothermal conversion material for the solar steam generation,the PCMPAs-PPy can achieve 80% energy conversion efficiency under the illumination intensity of 1 kW m-2.(4)Conjugated microporous polymers nanotubes carbon aerogels,CMPCA-1 and CMPCA-2 were obtained by carbonization of CMPA-1 and CMPA-2 under 600?.The BET specific surface areas of were measured to be 826 m2 g-1 for CMPCA-1 and509 m2 g-1 for CMPCA-2,respectively.The porosity of these two carbon aerogels was found to be 92.1% for CMPCA-1 and 91.7% for CMPCA-2,and the thermal conductivity was calculated to be 0.192 W m-1 k-1 for CMPCA-1 and 0.189 W m-1 k-1for CMPCA-2,respectively.Based on the higher specific surface area and porosity,lower thermal conductivity,stronger light absorption and faster water molecule transporation characteristics,the CMPCA-1 and CMPCA-2 show high performance for the solar steam generation.The energy conversion efficiency of CMPCA-1 and CMPCA-2 under 1 kW m-2 illumination was found to be 86.8% and 81% respectively.