Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6272, USA.
J Am Chem Soc. 2011 Jul 20;133(28):10826-31. doi: 10.1021/ja201405v. Epub 2011 Jun 24.
A series of sulfonate polyester ionomers with well-defined poly(ethylene oxide) spacer lengths between phthalates and alkali metal cations as counterions are designed for improved ionic conductivity. Ion conduction in these chemically complex materials is dominated by the polymer mobility and the state of ionic aggregation. While the aggregation decreases dramatically at room temperature as the cation size increases from Li to Na to Cs, the extents of ionic aggregation of these ionomers are comparable at elevated temperatures. Both the Na and Cs ionomers exhibit thermally reversible transformation upon heating from 25 to 120 °C as isolated ion pairs aggregate. This seemingly counterintuitive aggregation of ions on heating is driven by the fact that the dielectric constant of all polar liquids decreases on heating, enhancing Coulomb interactions between ions.
设计了一系列具有明确的聚（氧化乙烯）间隔长度的磺酸盐聚酯离聚物，邻苯二甲酸酯和碱金属阳离子作为抗衡离子，以提高离子电导率。在这些化学结构复杂的材料中，离子传导主要由聚合物的迁移率和离子聚集状态决定。尽管随着阳离子尺寸从 Li 增加到 Na 再增加到 Cs，在室温下，聚集程度显著降低，但在高温下，这些离聚物的离子聚集程度相当。Na 和 Cs 离聚物在从 25°C 加热到 120°C 时都会发生热可逆转变，因为孤立的离子对聚集在一起。在加热时离子似乎反常地聚集，这是因为所有极性液体的介电常数随温度升高而降低，从而增强了离子之间的库仑相互作用。
