Althumayri Khalid, Harrison Wayne J, Shin Yuyoung, Gardiner John M, Casiraghi Cinzia, Budd Peter M, Bernardo Paola, Clarizia Gabriele, Jansen Johannes C
School of Chemistry, University of Manchester, Manchester M13 9PL, UK.
Manchester Institute of Biotechnology and School of Chemistry, University of Manchester, Manchester M1 7DN, UK.
Philos Trans A Math Phys Eng Sci. 2016 Feb 13;374(2060). doi: 10.1098/rsta.2015.0031.
Gas permeability data are presented for mixed matrix membranes (MMMs) of few-layer graphene in the polymer of intrinsic microporosity PIM-1, and the results compared with previously reported data for two other nanofillers in PIM-1: multiwalled carbon nanotubes functionalized with poly(ethylene glycol) (f-MWCNTs) and fused silica. For few-layer graphene, a significant enhancement in permeability is observed at very low graphene content (0.05 vol.%), which may be attributed to the effect of the nanofiller on the packing of the polymer chains. At higher graphene content permeability decreases, as expected for the addition of an impermeable filler. Other nanofillers, reported in the literature, also give rise to enhancements in permeability, but at substantially higher loadings, the highest measured permeabilities being at 1 vol.% for f-MWCNTs and 24 vol.% for fused silica. These results are consistent with the hypothesis that packing of the polymer chains is influenced by the curvature of the nanofiller surface at the nanoscale, with an increasingly pronounced effect on moving from a more-or-less spherical nanoparticle morphology (fused silica) to a cylindrical morphology (f-MWCNT) to a planar morphology (graphene). While the permeability of a high-free-volume polymer such as PIM-1 decreases over time through physical ageing, for the PIM-1/graphene MMMs a significant permeability enhancement was retained after eight months storage.
文中给出了在固有微孔聚合物PIM-1中，少量层石墨烯混合基质膜（MMM）的气体渗透数据，并将结果与之前报道的PIM-1中其他两种纳米填料的数据进行了比较：用聚乙二醇功能化的多壁碳纳米管（f-MWCNTs）和熔融石英。对于少量层石墨烯，在极低的石墨烯含量（0.05体积%）下观察到渗透率显著提高，这可能归因于纳米填料对聚合物链堆积的影响。在较高的石墨烯含量下，渗透率下降，这是添加不可渗透填料时预期的情况。文献中报道的其他纳米填料也会导致渗透率提高，但在显著更高的负载量下，f-MWCNTs的最高测量渗透率为1体积%，熔融石英为24体积%。这些结果与以下假设一致：聚合物链的堆积受纳米填料表面在纳米尺度上的曲率影响，从或多或少的球形纳米颗粒形态（熔融石英）到圆柱形形态（f-MWCNT）再到平面形态（石墨烯），这种影响越来越明显。虽然像PIM-1这样的高自由体积聚合物的渗透率会随着时间通过物理老化而降低，但对于PIM-1/石墨烯MMM，在储存八个月后仍保留了显著的渗透率提高。
