Akiyama, Ryo Yokota, Naoki Otsuji, Kanji Miyatake, Kenji Structurally Well-Defined Anion Conductive Aromatic Copolymers: Effect of the Side-Chain Length For improving the alkaline stability and other properties of aromatic semiblock copolymer [QPE-<i>bl</i>-11a­(C1)] membranes containing benzyltrimethyl­ammonium groups, several novel hydrophilic monomers with different side-chain lengths and substitution positions were designed and synthesized for the polymerization. The pendant-type preaminated copolymers PE-<i>bl</i>-11s were quaternized using iodomethane to obtain the target QPE-<i>bl</i>-11s with well-defined chemical structure. In TEM analyses, QPE-<i>bl</i>-11a­(C3) and QPE-<i>bl</i>-11a­(C5) membranes with propyl and pentyl side-chains, respectively, showed more developed phase-separated morphology with greater hydrophilic domains (ca. 10–20 nm in width) than that of the C1 equivalent. The phase separation was more distinct and larger for the QPE-<i>bl</i>-11a membranes linked with <i>p</i>-phenylene groups in the hydrophilic part than for the QPE-<i>bl</i>-11b membranes with <i>m</i>-phenylene groups. In particular, QPE-<i>bl</i>-11b­(C5) membrane exhibited considerably smaller hydrophilic/hydrophobic domains compared to those of the other membranes. After the alkaline stability test in 1 M KOH aqueous solution at 60 °C for 1000 h, the remaining conductivity was better as increasing the side-chain length: 34% for QPE-<i>bl</i>-11a­(C1), 54% for QPE-<i>bl</i>-11a­(C3), and 72% for QPE-<i>bl</i>-11a­(C5) at 60 °C. The results suggest that the pendant alkyl chains could improve the alkaline stability and the main-chain bond position could improve morphology, water utilization, and mechanical properties of QPE-<i>bl</i>-11 membranes. An H<sub>2</sub>/O<sub>2</sub> fuel cell with QPE-<i>bl</i>-11 membrane showed 139 mW cm<sup>–2</sup> of the maximum power density at 0.28 A cm<sup>–2</sup> of the current density. bl -11 membrane;Structurally Well-Defined Anion Conductive Aromatic Copolymers;QPE;bl -11 b membranes;main-chain bond position;pendant alkyl chains;pendant-type preaminated copolymers PE;TEM;bl -11 membranes;phenylene groups;C 1 equivalent;1 M KOH;bl -11 2018-04-25
    https://acs.figshare.com/articles/journal_contribution/Structurally_Well-Defined_Anion_Conductive_Aromatic_Copolymers_Effect_of_the_Side-Chain_Length/6185354
10.1021/acs.macromol.8b00284.s001