Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States.
Department of Chemical Engineering and Material Science, Wayne State University , Detroit, Michigan 48202, United States.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):1173-1186. doi: 10.1021/acsami.7b13542. Epub 2017 Dec 19.
Multiblock poly(arylene ether sulfone) copolymers are attractive for polyelectrolyte membrane fuel cell applications due to their reportedly improved proton conductivity under partially hydrated conditions and better mechanical/thermal stability compared to Nafion. However, the long hydrophilic sequences required to achieve high conductivity usually lead to excessive water uptake and swelling, which degrade membrane dimensional stability. Herein, we report a fundamentally new approach to address this grand challenge by introducing shape-persistent triptycene units into the hydrophobic sequences of multiblock copolymers, which induce strong supramolecular chain-threading and interlocking interactions that effectively suppress water swelling. Consequently, unlike previously reported multiblock copolymer systems, the water swelling of the triptycene-containing multiblock copolymers did not increase proportionally with water uptake. This combination of high water uptake and low swelling behavior of these copolymers resulted in excellent proton conductivity and membrane dimensional stability under fully hydrated conditions. In particular, the triptycene-containing multiblock copolymer film with the longest hydrophilic block length (i.e., BPSH100-TRP0-15k-15k) had a water uptake of 105%, an excellent proton conductivity of 0.150 S/cm, and a volume swelling ratio of just 29% (more than 42% reduction compared to Nafion 212).
多嵌段聚（芳醚砜）共聚物因其在部分水合条件下据称具有更高的质子传导率和比 Nafion 更好的机械/热稳定性，因此在聚合物电解质膜燃料电池应用中具有吸引力。然而，为了实现高电导率而需要的长亲水性序列通常会导致过度的水吸收和溶胀，从而降低膜的尺寸稳定性。在此，我们报告了一种通过将形状稳定的三并苯单元引入多嵌段共聚物的疏水性序列中来解决这一重大挑战的全新方法，这会诱导强烈的超分子链缠结和互锁相互作用，从而有效地抑制水的溶胀。因此，与之前报道的多嵌段共聚物系统不同，含三并苯的多嵌段共聚物的水溶胀并没有随吸水率成比例增加。这些共聚物的高吸水率和低溶胀行为的结合，在完全水合条件下实现了优异的质子传导率和膜尺寸稳定性。特别是，具有最长亲水性嵌段长度的含三并苯多嵌段共聚物膜（即 BPSH100-TRP0-15k-15k）的吸水率为 105%，质子电导率为 0.150 S/cm，体积溶胀率仅为 29%（与 Nafion 212 相比降低了 42%以上）。
