Kruse Jan, Rätzke Klaus, Faupel Franz, Sterescu Dana M, Stamatialis Dimitrios F, Wessling Matthias
Lehrstuhl für Materialverbunde, Technische Fakultät der Christian-Albrechts-Universität zu Kiel, Kaiserstrasse 2, 24143 Kiel, Germany.
J Phys Chem B. 2007 Dec 20;111(50):13914-8. doi: 10.1021/jp074966+. Epub 2007 Nov 29.
PPO (poly(2,6-dimethyl-1,4-phenylene oxide)) is a well-known membrane material showing good gas separation properties. The incorporation of nanoparticles can enhance or deteriorate the performance of composite membranes, sometimes depending only on the way of the composite preparation. We have modified the PPO polymer with C60 fullerenes up to a content of 2 wt %. Previous investigations showed a strong dependence of permeability on whether the C60 is simply dispersed in the polymer or chemically bonded to the polymer chains. Free volume effects were suggested as an explanation but not experimentally confirmed. Here, we present free volume studies by positron annihilation lifetime spectroscopy. An additional long positron lifetime shows the increased free volume of composite samples, while the high electron affinity of C60 helps to indicate the homogeneity of the samples. Combining the presented results with permeability measurements refines the understanding of this promising membrane material.
聚（2,6-二甲基-1,4-亚苯基氧化物）（PPO）是一种众所周知的具有良好气体分离性能的膜材料。纳米颗粒的加入可以增强或降低复合膜的性能，有时仅取决于复合制备的方式。我们用C60富勒烯对PPO聚合物进行了改性，含量高达2 wt%。先前的研究表明，渗透率强烈依赖于C60是简单地分散在聚合物中还是化学键合到聚合物链上。有人提出自由体积效应作为一种解释，但尚未得到实验证实。在这里，我们通过正电子湮没寿命谱进行自由体积研究。一个额外的长正电子寿命表明复合样品的自由体积增加，而C60的高电子亲和力有助于表明样品的均匀性。将所呈现的结果与渗透率测量结果相结合，有助于深化对这种有前景的膜材料的理解。
