N-取代对聚苯并咪唑水/盐传输行为的影响研究  

Effects of N-substitution on the Water/Salt Transport Properties of Polybenzimidazole

作　　者：陈思 张琛琛 孟建强[1] Si Chen;Chen-chen Zhang;Jian-qiang Meng(State Key Laboratory of Separation Membranes and Membrane Processes,School of Materials Science and Engineering,Tiangong University,Tianjin 300387)

机构地区：[1]天津工业大学材料科学与工程学院、省部共建分离膜与膜过程国家重点实验室,天津300387

出　　处：《高分子学报》2023年第10期1588-1598,共11页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号22075206,21875162)资助项目。

摘　　要：为了解N-取代对聚苯并咪唑(PBI)水/盐传输行为的影响,考虑PBI中咪唑环上的N―H键较为活泼,选择3种具有可对比性的N-取代基团(对联苯甲酰基、对联苯磺酰基、丁烷基)与PBI中N―H基团反应,用核磁、傅里叶红外光谱、X-射线衍射、示差扫描量热和表面电势考察了N-取代后PBI的物化性质,并以溶解-扩散理论为基础,研究不同N-取代基团对PBI聚合物膜的水/盐传输行为的影响.研究结果表明,N-取代改性使聚合物链之间的相互作用降低,聚合物分子链间距增大,同时膜表面电负性增强.同时,与PBI相比,N-取代改性使得PBI分子链间产生更大的自由体积空穴,增加了水的传输通道,并提高亲水基团的可及性而降低自由水的含量,从而能够有效提高PBI膜的水/盐溶解、扩散和渗透选择性.其中,对联苯磺酰基其扩散水渗透系数与PBI相比提高了30倍,表现出最优异的水/盐传输性质.为了解聚合物改性对PBI水/盐传输性质的影响,也为未来面向脱盐高性能聚合物的分子结构设计提供了参考.In order to understand the effects of N-substitution on the water/salt transport behavior of polybenzimidazole(PBI),in this work,considering that the N―H bond on the imidazole ring in PBI is reactive,three comparable N-substituted groups(p-benzoyl,p-benzenesulfonyl,and butyl)were selected to react with the N―H group,and the physical and chemical properties of PBI after N-substitution were investigated by nuclear magnetic resonance(NMR),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),differential scanning calorimetry(DSC)and surface zeta potential,and solution-diffusion theory to investigate the effects of different N-substituted groups on the water/salt transport behavior of PBI.The results show that the N-substitution modification leads to the reduction of interactions between polymer chains and the increase of polymer molecular chain spacing,while the electronegativity of the membrane surface is enhanced.At the same time,the N-substitution modification results in larger free volume cavities between PBI molecular chains,which increase the water transport channels,and increases the accessibility of hydrophilic groups and decreases the content of free water;thus,it can improve the water/salt solubility,diffusivity and permeability selectivity of PBI effectively.Among them,p-biphenylsulfonyl whose diffusive water permeability coefficient is 30 times higher compared with PBI,exhibits the most excellent water/salt transport properties.It provides an understanding of the effect of polymer modification on the water/salt transport properties of PBI,and also provides a reference for future molecular structure design of high performance polymers oriented to desalination.

关 键 词：聚苯并咪唑 N-取代 溶解-扩散理论 水/盐传输 脱盐 

分 类 号：O633.5[理学—高分子化学]