Synthesis And Application Of Covalent Organic Porous Polymers Based On Triphenylimidazoles

Covalent organic porous polymers?COPs?usually include conjugated microporous polymers?CMPs?,polymers of intrinsic microporosity?PIMS?and hyper-crosslinked polymers?HCPS?.Compared with other polymers,COPs have the following advantages such as low density,high specific surface area,high porosity,strong adsorption ability,and difficult to decompose.Considering that triphenylimidazole derivatives have rigid molecular structure.Meanwhile,imidazole ring can complex with metal ions as well as can react with alkyl halides,which facilitate to broaden the scope of application of COP materials.In this thesis,two types of COPs were synthesized using triphenylimidazole derivatives as the building blocks.The main research contents are shown as follows:?1?Synthesis of covalent organic porous polymers?PTBPIs?by Yamamoto reaction.Firstly,we designed and synthesized three kinds of N-alkyl substituted triphenylimidazole derivatives,2,4,5-tris-?4-bromophenyl?^-1-alkyl^-1H-imidaole?alkyl R =-CH3,-CH2CH3,and-?CH2?3CH3;denoted as TBPI-Me,TBPI-Et,and TBPI-Bu,respectively?.And then three types of COPs such as PTBPI-Me,PTBPI-Et and PTBPI-Bu were synthesized by Yamamoto coupling reaction using TBPI-Me,TBPI-Et,and TBPI-Bu as the building blocks and bis-?1,5-cyclooctadiene?nickel?0?as the catalyst.It was found that the BET surface areas of PTBPI-Me and PTBPI-Et were close to each other and found to be 512.20 m² g^-1 and 477.30 m² g^-1,respectively,with total pore volume of 0.35 cm3 g^-1 and 0.36 cm3 g^-1.As for the PTBPI-Bu sample,its BET surface area and total pore volume were decreased to 34.09 m² g^-1 and 0.13 cm3 g^-1,respectively.At 273 K and 1 bar the CO₂ uptakes for the PTBPI-Me,PTBPI-Et and PTBPI-Bu were 1.99 mmol g^-1,1.80 mmol g^-1 and 0.96 mmol g^-1,respectively.In addition,the PTBPI-[Mmim][I] ionic salt was further prepared by reacting PTBPI-Me with CH3 I.The BET surface area and total pore volume of the PTBPI-[Mmim][I] were decreased to 22.39 m² g^-1 and 0.09 cm3 g^-1,respectively.On the basis of above analysis,the BET surface area,total pore volume,and adsorption capacity of PTBPIs can be roughly-tuned by the size of substituted groups on imidazole ring.?2?Synthesis of covalent organic porous polymers?PTCPIs?by trimerization of nitrile.Firstly,2,4,5-tris?4-cyanophenyl?^-1-alkyl^-1H-imidazole derivatives?alkyl R =-H,-CH3,-CH2CH3,and-?CH2?3CH3,denoted as TCPI-H,TCPI-Me,TCPI-Et,and TCPI-Bu,respectively?.Then four types of COPs including PTCPI-H,PTCPI-Me,PTCPI-Et,and PTCPI-Bu were synthesized by trimerization of nitrile at 500 oC using TCPI-H,TCPI-Me,TCPI-Et,and TCPI-Bu as the building blocks and ZnCl2 as the catalyst.The experimental results showed that the PTCPI-H sample possessed the highest BET surface area of 1463.9 m² g^-1,followed by PTCPI-Me and PTCPI-Et samples with similar BET surface areas of 1366.40 m² g^-1 and 1347.83 m² g^-1.The PTCPI-Bu sample,however,possessed the lowest BET surface area of 1080.86 m² g^-1.The CO₂ uptake for the PTBPI-Me sample was 2.02 mmol g^-1 at 298 K.Post-modification of PTCPIs by using nitration reaction and attachment of nitro groups to part of phenyl rings yield nitrified PTCPIs?PTCPIs-NO₂?.The surface areas of PTCPI-H-NO₂,PTCPI-Me-NO₂,PTCPI-Et-NO₂ and PTCPI-Bu-NO₂ were decreased to 1074.27 m² g^-1,1138.95 m² g^-1,1085.11 m² g^-1,and 824.39 m² g^-1.But the adsorption capacity of CO₂ for the PTCPI-Me-NO₂ sample at 298 K was increased to 2.20 mmol g^-1.On the basis of above analysis,the BET surface area and adsorption capacity of PTCPIs can be roughly-tuned by the post-modification.