Study On The Preparation And Properties Of Porous Polymers Based On Organosilicon Compounds

Covalent organic microporous materials based on triazine rings（CTFs）possess many excellent advantages:high specific area,low skeleton density,good thermal stability,easy to tailor pore and so on,popular in the fields of gas adsorption and separation,polluted water treatment,biosensor,etal.But at present the available building modules to synthesize the CTFs materials are mainly aromatic nitrile compounds,limiting the types of that,and due to the particularity of its structure,it is difficult to modify that,to some extent,which greatly limits the kinds of the CTFs materials and the ranges of its application,therefore,it is very necessary to design to prepare more building monomers suitable for synthesis the CTFs,and to realize their functionalization.On my work,we will combine aromatic nitrile compounds with organic silanes,to design and obtain novel building units for the CTFs,finally to synthesize a series of triazine-based covalent organic microporous materials containing silanes（Si-CTFs）,optimizing its preparation conditions,studying the possibility of its functionalization,and exploring its application value in gas adsorption and waste water treatment.This article firstly use four chlorosilanes with different structures,under the assist of n-butyl lithium,to react with 4-bromobenzonitrile and produce four new kinds of silane monomers containing benzonitrile with corresponding structures:the methyltri（4-cyanophenyl）silane,the dimethyldi（4-cyanophenyl）silane,the vinyltri（4-cyanophenyl）silane and the methylvinyldi（4-cyanophenyl）silane,by¹H-NMR,¹³C-NMR,FTIR and elemental analysis analyzing their structure,as a result,it proves that we successfully prepare the new four kinds of silanes.We firstly study on the optimum synthesis for the CTFs through the reaction of the methyltri（4-cyanophenyl）silane and the dimethyldi（4-cyanophenyl）silane under the condition of molten zinc chloride as catalyst.The result have shown that the nitrile group reaction is incomplete at the temperature of 300oC,resulting in the poor pore properties of the resulting polymers.When raising the temperature to 400oC,the residual of the nitrile group can be eliminated,and finally the perfect crosslinking Si-CTFs are be synthesized with the specific surface areas of 774 and 381 m² g^-1,respectively.XRD,SEM and TEM tests show that the two Si-CTFs are amorphous polymers,and Thermogravimetric analysis proves that the two Si-CTFs have excellent thermal stability.The CO₂ adsorption and desorption experiments show that Si-CTF-1 has a high CO₂ adsorption capacity(54.4 cm³ g^-1).Furthermore,Si-CTF-1also has excellent Methylene Blue（MEB）adsorption performance,and its equilibrium adsorption capacity can reach 648.9 mg g^-1,its adsorption kinetics and isothermal adsorption models are in accordance with the Pseudo-second-order kinetic and Langmuir models,respectively.In order to realize the functionalization of the materials,we synthesized two kinds of porous polymers Si-CTF-3 and Si-CTF-4 by using the vinyltri（4-cyanophenyl）silane and the methylvinyldi（4-cyanophenyl）silane,hoping that modification of the resulting polymers will be completed through the introduction of vinyl group.However,the analysis shows that the vinyl groups cannot be retained in the polymerization reaction,so the functionalization of the materials cannot be completed by this method.The specific surface area pore size analyzer result indicates that the two materials has specific areas of 383 and 500 m² g^-1,respectively,in addition,their carbon dioxide adsorption capacities were 28.7 and 20.7 cm³ g^-1,respectively.Si-CTF-4 were applied to the Congo Red（CR）adsorption experiment,and its maximum adsorption capacity was 640 mg g^-1.The adsorption mechanism was in accordance with the Pseudo-second-order kinetic and the Langmuir models.The research contents of this paper provide a new research idea for the preparation of the triazine-based porous polymer materials,and study on the functionalization of the porous polymers,which make a significance meaning in the development of this kind of materials.