Ultrathin Polymer Films with Intrinsic Microporosity: Anomalous Solvent Permeation and High Flux Membranes
Ultrathin Polymer Films with Intrinsic Microporosity: Anomalous Solvent Permeation and High Flux Membranes
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DOI：
10.1002/adfm.201400400
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发表时间：
2014-08-13
影响因子：
19
通讯作者：
Livingston, Andrew G.
中科院分区：
文献类型：
--
作者：
Gorgojo, Patricia;Karan, Santanu;Livingston, Andrew G.
介绍了一种由本征微孔聚合物（PIM-1）制备的具有厚度为35 nm的微孔分离层的有机溶剂纳滤膜（OSN）。这些膜表现出非常快的渗透正庚烷与约90%的六苯基苯的排斥。35 nm厚的PIM-1膜具有222 MPa的杨氏模量，并且在OSN中在高达15巴的液压下显示出优异的稳定性。用140 nm厚的膜实现了18 Lm（-2）h（-1）bar（-1）的正庚烷的最大渗透性，这比Starmem 240（商业聚酰亚胺基OSN膜）高约两个数量级。出乎意料的是，将膜厚度降低到140 nm以下导致渗透率的异常降低，这似乎与PIM-1的堆积增强有关，如通过光干涉测量法所测量的。此外，由PIM-1形成的膜的热退火揭示了它们的渗透性在超过150 ℃的温度下保持不变，而常规的整体结皮的不对称聚酰亚胺OSN膜的渗透性在相同条件下退火时显著降低。为了合理化这一关键差异的功能性能退火的反应，膜与固有微孔性（MIMs）与膜与外在微孔性（MEMs）的概念被引入。
Organic solvent nanofiltration (OSN) membranes with ultrathin separation layers down to 35 nm in thickness fabricated from a polymer of intrinsic microporosity (PIM-1) are presented. These membranes exhibit exceptionally fast permeation of n-heptane with a rejection for hexaphenylbenzene of about 90%. A 35 nm thick PIM-1 membrane possesses a Young's modulus of 222 MPa, and shows excellent stability under hydraulic pressures of up to 15 bar in OSN. A maximum permeance for n-heptane of 18 Lm(-2)h(-1) bar(-1) is achieved with a 140 nm thick membrane, which is about two orders of magnitude higher than Starmem240 (a commercial polyimide-based OSN membrane). Unexpectedly, decreasing the film thickness below 140 nm results in an anomalous decrease in permeance, which appears to be related to a packing enhancement of PIM-1, as measured by light interferometry. Further, thermal annealing of the membranes formed from PIM-1 reveals that their permeance is preserved up to temperatures in excess of 150 degrees C, whereas the permeance of conventional, integrally skinned, asymmetric polyimide OSN membranes decreases significantly when they are annealed under the same conditions. To rationalize this key difference in response of functional performance to annealing, the concept of membranes with intrinsic microporosity (MIMs) versus membranes with extrinsic microporosity (MEMs) is introduced.