Preparation And Properties Of Aromatic Hyperbranched Polymer Gas Separation Membranes

For gas separation and capture,membrane separation offers a potential alternative to both cryogenic distillation and swing absorption.But gas membrane separation still has some limitations,including poor stability,fussy pretreatment,and only being valid for a certain gas pair.The aromatic hyperbranched polymers attract our interest,due to their excellent chemical and thermal stability.Finally,three kinds of hyperbranched polymers have been synthesized and were applied in gas separation.（1）The PHT membrane was prepared by thermal annealing the hemiaminal dynamic covalent networks（HDCNs）membrane which was synthesized from 4,4’-oxydianiline（ODA）and paraformaldehyde（PFA）in water/NMP solution.PHT membrane has the degradation temperature（T_d）of 250℃exhibits an excellent thermal stability.Its O₂,CO₂ and N₂ permeabilities are 6.57,8.71 and 2.47 Barrer respectively,and the perm-selectivity of O₂/N₂ and CO₂/N₂ are 2.66 and 3.53.PHT membrane could be successful degraded in 1 M HCl solution（p H=0）in 2 h,realizing the recovery of ODA.（2）A template free method have been developed for preparing the hyperbranched polyimide（PI）microspheres by coprecipitation tris（4-aminophenyl）amine（TAPA）and pyromellitic（PMDA）in acetone solution.As a result of the post-treatment condition,the specific surface area varies from 170.31 to 585.67 m~2/g for the PI microspheres with a T_d of 480°C.Then,PI microspheres were blend into the polyetherimide（PEI）matrix to form a mixed matrix membrane（MMM）names as PEI/PX-Y%.Finally,PEI/P9-10%showed the best separation performance,having the N₂,O₂ and CO₂ permeabilities of107.32,532.09 and 1653.92 Barrer and O₂/N₂ and CO₂/N₂ selectivity of6.08 and 15.41.Its O₂/N₂ separation performance successfully surpass the Robeson’s upper limit of in2008,showing a great potential in industrial application.（3）The hollow,spherical covalent organic framework（COF）which was prepared using 1,3,5-Tris（4-aminophenyl）benzene（TAPB）and p-Phenylenediamine（PDA）was used as the filler in the PEI MMM membrane.These COF microspheres show good affinity to the PEI matrix.The MMM membrane that contains the COF up to 50 wt%,the permeability of N₂,O₂ and CO₂ could reach 98.20,663.83 and 1584.95 Barrer.The selectivity of O₂/N₂ and CO₂/N₂ was 5.34 and 16.14,respectively.The COF in PEI matrix can greatly improve the gas permeability,and overcome the trade-off effect between permeability and selectivity.