Resarch On Synthesis,Structures And Properties Of Polymers Via Coal Based Aromatics And Its Derivatives

China is rich in coal resources,which are the storehouse of various alkyl substituted benzenes（ASBs）and polycyclic aromatic hydrocarbons（PAHs）.Various types of methyl substituted benzenes（MSBs）and PAHs with great quality can be separated from coal and coal tar under mild conditions.Although a large number of downstream products produced based on ASBs,especially MSBs,and PAHs as raw materials are technically mature,there is still a large space for research and development in the MSBs and PAHs high-value-added utilization,such as preparation of multi-functional polymer materials,porous materials,etc.,so as to further improve the industrial chain of coal resources high-value-added utilization and promote the rationalized coal resources utilization from the opposite direction.In this project,a series of high-value-added polymers were prepared by using simple symmetrical PAHs and their derivatives separated from coal and coal tar as raw materials,through Friedel-Crafts alkylation,Scholl coupling and Suzuki-Miyaura coupling reaction under mild reaction conditions with cheap and easily available catalysts.The prepared polymers show great properties in heat resistance,adsorption,fluorescence and other aspects.The products feature cheap raw materials,facile preparation and can be used as the precursor for further development of various functional materials.Specifically:（1）In this paper,benzyl chloride was used as raw material to explore the way of copolymerization with benzene under mild conditions to prepare polymers with outstanding thermal stability and excellent fluorescence performance.According to the reaction scheme optimization,it was determined thatα-Fe₂O₃/attapulgite（α-Fe₂O₃/A）-catalyzed benzene in CCl₄ at 100 ℃ for 4 h is the standard conditions of the experiment.The free radical trapping agent such as tetramethylpiperidine nitrogen oxide or dibutylhydroxytoluene is added to the standard reaction as controlling experiments in pursuit of the reaction mechanism,and the cation reaction mechanism is deduced.The recycledα-Fe₂O₃/A from the experiment can still catalyze the polymerization of benzyl chloride wirh benzene after three cycles of activation of recovery,washing,acidification and calcination,which is of strong catalytic activity and great value in use.With the help of modern analytical methods including ultraviolet spectroscopy,Fourier transform infrared spectroscopy（FTIR）,liquid nuclear magnetic resonance（NMR）,elemental analysis,gel chromatography（GPC）,thermogravimetric analysis（TGA）,X-ray diffraction and fluorescence spectroscopy,the products were proved to be of excellent properties,such as structure,high molecular weight,low polymer dispersity index（PDI）,high decomposition temperature,amorphous structure and strong fluorescence.According to the investigation on benzyl chloride,the products were prepared via a two-step strategy,namely photohalogenation and thermal polymerization,based on symmetrical MSBs such as p-xylene,mesitylene and durene.The structure and other properties of the products are characterized by the above analysis methods.The prepared polymers also feature high molecular weight,low PDI,high decomposition temperature,amorphous structure and strong fluorescence.All these products possess good thermal stability and can be further used in the preparation of carbon materials.（2）The hyper-cross-linked microporous polymers（HCLMPs）1-4 were prepared based on naphthalene via 3 methods,namely external cross-linker（ECL）method,solvent knitting method and Scholl coupling reaction.1,4-Dimethoxybenzene（DMB）and DMM were adopted as cross-linkers in the ECL method.Reaction process and preparation of corresponding products were confirmed by the UV spectra,FTIR and ¹³C solid cross polarized magic angle rotating nuclear magnetic resonance(¹³C CP/MAS NMR).The preparation of HCLMPs 1-4 can be amplified to gram-scale with almost the isolated yield unchanged.HCLMPs 1-4 were characterized by scanning electron microscopy,TGA as well as fluorescence spectroscopy.HCLMPs 1-4 are found insoluble in all organic reagents except THF.Scanning electron microscopy images confirm that the products are amorphous and of porous structures with small spherical particles accumulated together.TGA shows that the polymers possess good thermal stability with more than 70%residue remaining at 900 ℃,which are potential precursors for carbon materials preparations.Fluorescence spectroscopy prove that the products are of excellent fluorescence.The N₂ adsorption/desorption isotherms show that the products generally feature high specific surface areas and small pore size,and some products even possess micropores with pore size less than 0.7 nm,which are of great advantages in CO₂ adsorption.HCLMP 2,prepared via ECL method by adopting DMM as cross-linker,owned the largest Brunauer-Emmett-Teller（BET）specific surface area up to 2870 m² g^-1.Further characterization found HCLMP 2 possess the adsorption capacity of CO₂（273 K）up to 55.42 cm³ g^-1 and H₂（77 K）up to 121.54 cm³ g^-1,which show great potential for gas storage.HCLMPs 5-12 were prepared via the above 3 methods by adopting 1-methylnaphthalene and 1-naphthol as raw materials to investigate the influence of substituents on the preparation of HCLMPs.Reaction process and preparation of corresponding products were also confirmed by the UV spectra,FTIR and ¹³C CP/MAS NMR and other analytical methods.The products were characterized by scanning electron microscopy,TGA,fluorescence spectroscopy and N₂ adsorption/desorption isotherms.Scanning electron microscopy images showed that HCLMPs 5-12 are mainly composed of flake materials,which resulted from the function groups on naphthalene rings that make the morphology and size of HCLMPs irregular.TGA shows that the product still remain good thermal stability,and fluorescence spectra show that HCLMPs 5-12 are fluorescent.However,the N₂ adsorption/desorption isotherms show that introducing-CH₃ into the raw materials has little effect on the pore structure of the final product,while only via ECL method based on raw materials with–OH can prepared HCLMPs possess equivalent pore structure properties with HCLMPs 1-4.After comprehensive analysis,it is found that ECL method is the best way to prepare HCLMPs,especially by adopting DMM as cross-linker.What’s more,naphthalene is the most suitable monomer to prepare HCLMPs,and the introduction of substituents into raw materials has little effect on the properties of the products with appropriate preparation method.（3）A series of conjugated microporous polymers（CMPs）were prepared via Pd-catalyzed Suzuki-Miyaura coupling reaction based on different functional organobromides and organoboron reagents.The coupling process and the preparation of CMPs were confirmed by UV spectra,FTIR and ¹³C CP/MAS NMR.CMPs were characterized by scanning electron microscopy,TGA and fluorescence spectra.The prepared polymers depended largly on the main structure of the synthetic monomer,especially organobromides.CMPs were composed of solid particles with different sizes in microstructure,showing excellent performance in chemical and thermal stability,and insoluble in common organic solvents,stable even in strong acid and alkali.There are more than 70%residue remaining of the prepared CMPs at 900 ℃ under Ar atmosphere,which are excellent precursors for further preparation of carbon materials.N₂ adsorption/desorption isotherms show that the materials are mainly microporous,with little mesoporous and macroporous structure.Compared with 1,3,5-tris（4-bromophenyl）benzene（TBPB）and 2,2’,7,7’-tetrabromo-9,9-spirobifluorene（TBSBF）,CMPs prepared from 1,3,6,8-tetrabromopyrene（TBP）showed better pore structures.CMPs prepared based on 1,4-phenyldibasic acid（PDBA）were also of better properties than those of 4,4-biphenyldibasic acid pinacol ester（BPDBA）and 1,3,5-phenyltriboronic acid,pinacol ester（TTDBB）.Therefore,TBP and PDBA are the preferred monomers for the preparation of CMPs with excellent performance.BP-Ph-CMP is the best product in the series of CMPs,with BET specific surface area up to 1071m²g^-1.Then,the H₂ storage and CO₂ capture capacity of BP-Ph-CMP are further investigated at 77 K and 273 K,respectively.BP-Ph-CMP possesses H₂ adsorption capacity up to 152.77 cm³ g^-1（at 77 K and 1 bar）as well as CO₂ adsorption capacity up to 58.97 cm³ g^-1（at 273 K and 1 bar）,which shows great potential in gas adsorption.