UV-Rearranged PIM-1 Polymeric Membranes for Advanced Hydrogen Purification and Production
UV-Rearranged PIM-1 Polymeric Membranes for Advanced Hydrogen Purification and Production
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DOI：
10.1002/aenm.201200296
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发表时间：
2012-12-01
影响因子：
27.8
通讯作者：
Chung, Tai-Shung
中科院分区：
文献类型：
--
作者：
Li, Fu Yun;Xiao, Youchang;Chung, Tai-Shung
固有微孔隙度聚合物（PIM-1）以其超高的渗透率和中等大小气体对的平均选择性而闻名。它们对H2和CO2的分离选择性不高（即，a (H2/CO2) = 0.6）。我们首次发现了PIM-1膜的紫外重排聚合物可用于H2/CO2分离，其分离性能远优于文献中其他聚合物。经紫外光照射4小时后，PIM-1膜H2通透性为452，H2/CO2选择性为7.3。实验数据和分子模拟表明，PIM-1的聚合物链在紫外线照射后发生1,2-迁移反应，转变为接近平面的重排结构。结果表明，紫外照射后的PIM-1膜的自由体积分数（FFV）和微孔大小均有明显下降。正电子湮灭寿命（PAL）结果证实了化学和结构上的变化，表明FFV和孔径的减小主要是由于紫外辐射破坏了螺碳中心。吸附和x射线衍射（XRD）分析表明，紫外辐射导致H2/CO2选择性显著增强，其次是分子重排、构象改变和链填充。
Polymers of intrinsic microporosity (PIM-1) have been known for their super high permeability but average selectivity for medium-size gas pairs. They have unimpressive selectivity for H2 and CO2 separation (i.e., a (H2/CO2) = 0.6). For the first time, we have discovered that ultraviolet (UV)-rearranged polymers of PIM-1 membranes can be used for H2/CO2 separation with far superior separation performance to others in literatures. The PIM-1 membrane after UV radiation for 4 hours shows H2 permeability of 452 barrer with H2/CO2 selectivity of 7.3. Experimental data and molecular simulation reveal that the polymer chains of PIM-1 undergo 1,2-migration reaction and transform to close-to-planar like rearranged structure after UV radiation. As a result, the UV-irradiated PIM-1 membrane shows considerable drops in both fractional free volume (FFV) and size of micro-pores. Positron annihilation lifetime (PAL) results have confirmed the chemical and structural changes, suggesting the FFV and pore size drops are mainly ascribed to the destructed spiro-carbon centre during UV radiation. Sorption and x-ray diffractor (XRD) analyses indicate that the impressive H2/CO2 selectivity arises from the significantly enhanced diffusivity selectivity induced by UV radiation, followed by molecular rearrangement, conformation change and chain packing.