碳纳米管/聚氨酯杂化膜的原位聚合构建及气体渗透性能

采用H2SO4/HNO3混酸处理得到不同氧化程度的多壁碳纳米管(MWCNT-COOH),再通过与4,4′-二苯基甲烷二异氰酸酯(MDI)、1,4-丁二醇(BDO)的预聚和扩链反应构建碳纳米管/聚氨酯(MWCNT-COOH/PU)杂化膜。利用傅里叶红外光谱(FTIR)、拉曼光谱(Raman)和透射电子显微镜(TEM)等分析表征多壁碳纳米管结构;探讨了多壁碳纳米管氧化程度和填充量对MWCNTCOOH/PU杂化膜的形貌和CO2、N2渗透性能的影响。结果表明,混酸处理后的多壁碳纳米管带有一定的含氧基团,并随氧化程度的提高,多壁碳纳米管的拉曼光谱G峰和D峰的强度之比(ID/IG)有所增大;氧化程度对多壁碳纳米管在溶剂和杂化膜中的分散性有较大影响,氧化程度越高,分散性越好;杂化膜的CO2、N2渗透性及CO2/N2渗透选择性随多壁碳纳米管氧化程度的增加有所增大,而随多壁碳纳米管填充量的增加表现出先增大后减小的趋势,当氧化程度较高的多壁碳纳米管(H-MWCNT-COOH)填充量为1.0wt%时,H-MWCNT-COOH/PU杂化膜的CO2渗透系数为67.8 Barrer,CO2/N2渗透选择性可达45,表明适量填充MWCNT-COOH能显著提高MWCNT/PU杂化膜的CO2渗透性及CO2/N2的渗透选择性。

Gas Permeation Property of MWCNT/Polyurethane Mixed Matrix Membranes Prepared by In Situ Polymerization

Multi-walled carbon nanotubes(MWCNT) were treated by HNO₃/H₂SO₄ mixture, which were then modified by in situ polymerization with methylene diphenyl 4,4'-diisocyanate (MDI) and 1,4-butanediol (BDO) to form a MWCNT/polyurethane (PU) mixed matrix membrane. The composition and structure of MWCNT-COOH were characterized by Fourier transform infrared (FTIR), Raman spectrum, Transmission electron microscopy (TEM). Streaming potential instrument was used to characterize the dispersion of MWCNT-COOH in dimethylformamide (DMF) solvent. The effect of oxidation degree and content of MWCNT-COOH on CO₂ and N₂ permeation of MWCNT-COOH/PU mixed matrix membranes was investigated. The results reveal that higher oxidation degree (H-MWCNT-COOH) could reduce the aggregation of MWCNT-COOH, thus improving their dispersion in the mixed matrix membranes. In addition, the CO₂, N₂ permeability and CO₂/N₂ permeation selectivity are obviously enhanced with increasing the oxidation degree of MWCNT-COOH. In the mixed matrix membrane with 1.0wt% H-MWCNT-COOH content, the CO₂ permeability is 67.8 Barrer and CO₂/N₂ permeation selectivity is 45, indicating the important role of the MWCNT-based additive in improvement of CO₂ permeability and selectivity to N₂.