Physical aging, CO2 sorption and plasticization in thin films of polymer with intrinsic microporosity (PIM-1)
Physical aging, CO2 sorption and plasticization in thin films of polymer with intrinsic microporosity (PIM-1)
复制标题
DOI：
10.1016/j.memsci.2017.04.069
复制
发表时间：
2017-09
影响因子：
9.5
通讯作者：
R. R. Tiwari-R.;Jianyong Jin;B. Freeman;D. R. Paul
中科院分区：
文献类型：
--
作者：
R. R. Tiwari-R.;Jianyong Jin;B. Freeman;D. R. Paul
通过监测 35 °C 固定温度下 O2、N2 和 CH4 纯气体渗透率的变化，研究了“高自由体积”玻璃聚合物 PIM-1（具有固有微孔性的聚合物）的厚膜和薄膜的物理老化。 PIM-1的渗透性对膜厚、后处理（甲醇浸泡、水浸泡或干燥）和浇铸溶剂（氯仿和邻二氯苯）非常敏感。 PIM-1 薄膜经历加速老化，导致初始磁导率比厚膜低一个数量级。由于薄膜的老化速率较高，老化 1000 小时后，PIM-1 薄膜的相对磁导率下降了 67%，而厚膜的相对磁导率下降了 53%。浇铸溶剂（蒸气压和沸点）对薄膜的老化和选择性的影响更加明显，用氯仿（CHCl3）浇铸的薄膜的初始渗透率几乎是用邻二氯苯（o-DCB）溶剂制备的薄膜的两倍。对于厚膜来说，浇铸溶剂对初始渗透性的影响不太明显。薄膜厚度、浇铸溶剂和 CO2 暴露方案也对厚膜和薄膜的绝对 CO2 渗透性和塑化行为有显着影响。与厚膜相比，塑化后薄膜的相对渗透性显着增加，并且发现即使在 CO2 减压过程中渗透性也会增加。长时间、恒压 CO2 暴露研究揭示了薄膜中的主要老化效应，其中老化在 CO2 暴露后 1.2 分钟内克服了 CO2 塑化效应，而厚膜则需要 10 小时。椭圆光度测量表明，薄膜中CO2的溶解度随着老化时间和温度的增加以及分子量的降低而降低。朗缪尔吸附容量CH'和无限稀释溶解度S0与PIM-1的老化时间、温度和分子量有很强的相关性。
Physical aging of both thick and thin films of “high free-volume” glassy polymer, PIM-1 (polymer with intrinsic microporosity) was studied by monitoring changes in pure gas permeability of O2, N2and CH4at a fixed temperature of 35 °C. Permeability of PIM-1 is very sensitive to film thickness, post-treatment (methanol soak, water soak or dried) and casting solvent (chloroform and ortho-dichlorobenzene). Thin films of PIM-1 undergo accelerated aging, leading to initial permeability lower by an order of magnitude compared to thick films. The relative permeability for thin films of PIM-1 was decreased by 67% compared to 53% decrease for thick films at 1000 h of aging due to the higher aging rates in thin films. The effect of casting solvent (vapor pressure and boiling point) is more pronounced on aging and selectivity of thin films with initial permeability almost two times higher for the film casted from chloroform (CHCl3) compared to that prepared from ortho-dichlorobenzene (o-DCB) solvent. The effect of casting solvent on the initial permeability is less prominent for thick films. The film thickness, casting solvent and CO2exposure protocols also have significant effect on the absolute CO2permeability and plasticization behavior of both thick and thin films. The thin films undergo significant increase in the relative permeability upon plasticization compared to thick films and permeability was found to increase even during CO2depressurization. The long time, constant pressure CO2exposure study revealed dominant aging effect in thin film where aging overcomes the CO2plasticization effect just within 1.2 min of the CO2exposure compared to 10 h for thick film. The ellipsometry measurements showed that the CO2solubility in thin films decreases with increases in the aging time and temperature, and with decrease in the molecular weight. A strong correlation was observed for the Langmuir sorption capacity,CH' and solubility at infinite dilution,S0with the aging time, temperature and molecular weight of PIM-1.