Design And Synthesis Of Porous Organic Polymers Applied In Electrochemistry

Porous organic polymers（POPs）,which are entirely composed of organic components,are new kinds of porous material in recent years.Comparing with metal-organic frameworks connected by coordinative bond,POPs linked by covalent bonds exhibit excellent stability while maintaining regular pore structure.Covalent organic frameworks（COFs）and conjugated microporous polymers（CMPs）are representive of POPs which can be designed at the molecular level to satify the needs of different applications,and have showcased great application prospects in the electrochemical fields,such as ionic conductivity,electron transport and energy storage etc.In this paper,dibenzo[g,p]chrysene（DBC）and 9,9’-bifluorenylidene（9,9’-BF）units were introduced into the skeleton of COFs and CMPs through a bottom-up approach,which exhibited good electrochemical properties.This paper is mainly divided into the following four parts:1.The imine-protected DBC-based monomer was designed and synthesized which was used to fabricated DBC-1P and DBC-2P via formal transamination reaction.These materials with dual-pore and kgm structure exhibited excellent chemical stability in strong acid,base and boiling water.The more planar and largerπ-conjugated DBC-unit could strengthen the interlayer stacking of 2D-COF nanosheets and thus increase the chemical stability of COFs.The linear polyethylene glycol（PEG）or PEG-Li BF₄ was encapsulated into the nanochannel of DBC-COFs and the thermal transition of PEG in the pore was changed because of confinement effect.The PEG-Li BF₄ confined hybrid material exhibited good ionic conductivity and this work demonstrates an efficient strategy for development of COF-polymer composites with intriguing properties.2.A new method was developed for the preparation of sulfonic acid modified aldehyde monomers（2P-SO₃H）by the nucleophilic substitution reaction of sulfites,and the ionic COFs with different pore structure and bearing with sulfonic acid was synthesized unsing 2P-SO₃H.At the same time,the modulation of pore-wall environment of BF-based COFs was realized by the functionality of aldehyde monomers.All sulfonic acid modified COFs exhibited excellent intrinsic proton conductivity without proton carriers.This method has great significance for the development of new ionic COFs and proton conductive materials.3.BF-based COF（BF-1P）with good ctystallinity and ordered microporous structure was designed and synthesized.The crystalline BF-1P thin film could be prepared by in-situ growth method.The HOMO level of BF-1P was calculated by cyclic voltammetry which matched the reduction potential of iodine and the oxidation of aromastic structure of BF-1P by iodine was demonstrated by FT-IR and Raman spectra.The photoconductivity coud be increased by the iodine dopoing and theφΣμwas improved two orders of magnitude and reached to 7.28×10^-6 cm² V^-1 s^-1 after doping I₂.This study has a certain reference significance for the preparation of conductive COFs and the study of chemical doping mechanism of these materials4.Two CMPs with excellent porosity,Poly（2,7-BF-Cz₄）and Poly（3,6-BF-Cz₄）,were prepared by the oxidation coupling of BF-based isomers bearing carbazol groups.The BET surface area and pore volume of Poly（2,7-BF-Cz₄）were 2105 m² g^-1 and1.40 cm³ g^-1.Thanks to the excellent stabilities of BF-based units and the large porosity of the polymer networks,Poly（2,7-BF-Cz₄）and Poly（3,6-BF-Cz₄）were used as efficient host materials for sulfur storage in Li-S batteries.Both Poly（2,7-BF-Cz₄）/S and Poly（3,6-BF-Cz₄）/S cathodes show good durabilities and diliver a large capacity of 724 and 668 m Ah g^-1 at 1 C after 400 cycles,with a low decaying rate of 0.044%and 0.071%per cycle,respectively.These results demonstrate that 9,9’-BF based networks can serve as promising cathode material for high-performance Li-S battery.