Nykaza Jacob R, Ye Yuesheng, Nelson Rachel L, Jackson Aaron C, Beyer Frederick L, Davis Eric M, Page Kirt, Sharick Sharon, Winey Karen I, Elabd Yossef A
Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA.
Soft Matter. 2016 Jan 28;12(4):1133-44. doi: 10.1039/c5sm02053k.
Herein, we examine the synergistic impact of both ion clustering and block copolymer morphology on ion conductivity in two polymerized ionic liquid (PIL) diblock copolymers with similar chemistries but different side alkyl spacer chain lengths (ethyl versus undecyl). When saturated in liquid water, water/ion clusters were observed only in the PIL block copolymer with longer alkyl side chains (undecyl) as evidenced by both small-angle neutron scattering and intermediate-angle X-ray scattering, i.e., water/ion clusters form within the PIL microdomain under these conditions. The resulting bromide ion conductivity in the undecyl sample was higher than the ethyl sample (14.0 mS cm(-1)versus 6.1 mS cm(-1) at 50 °C in liquid water) even though both samples had the same block copolymer morphology (lamellar) and the undecyl sample had a lower ion exchange capacity (0.9 meq g(-1)versus 1.4 meq g(-1)). No water/ion clusters were observed in either sample under high humidity or dry conditions. The resulting ion conductivity in the undecyl sample with lamellar morphology was significantly higher in the liquid water saturated state compared to the high humidity state (14.0 mS cm(-1)versus 4.2 mS cm(-1)), whereas there was no difference in ion conductivity in the ethyl sample when comparing these two states. These results show that small chemical changes to ion-containing block copolymers can induce water/ion clusters within block copolymer microdomains and this can subsequently have a significant effect on ion transport.
在此，我们研究了离子簇聚和嵌段共聚物形态对两种化学组成相似但侧链烷基间隔链长度不同（乙基对十一烷基）的聚合离子液体（PIL）二嵌段共聚物离子电导率的协同影响。当在液态水中饱和时，小角中子散射和中角X射线散射均表明，仅在具有较长烷基侧链（十一烷基）的PIL嵌段共聚物中观察到水/离子簇，即在这些条件下，水/离子簇在PIL微区内形成。十一烷基样品中得到的溴离子电导率高于乙基样品（在50℃液态水中分别为14.0 mS cm⁻¹和6.1 mS cm⁻¹），尽管两个样品具有相同的嵌段共聚物形态（层状），且十一烷基样品的离子交换容量较低（0.9 meq g⁻¹对1.4 meq g⁻¹）。在高湿度或干燥条件下，两个样品中均未观察到水/离子簇。与高湿度状态相比，具有层状形态的十一烷基样品在液态水饱和状态下的离子电导率显著更高（14.0 mS cm⁻¹对4.2 mS cm⁻¹），而比较这两种状态时，乙基样品的离子电导率没有差异。这些结果表明，对含离子嵌段共聚物进行微小的化学变化可在嵌段共聚物微区内诱导形成水/离子簇，这随后可对离子传输产生显著影响。
