Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
Soft Matter. 2016 Jun 28;12(24):5359-71. doi: 10.1039/c6sm00398b. Epub 2016 May 24.
Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.
基于聚（苯乙烯）的嵌段共聚物，带有侧基三甲基苯乙烯基丁基铵（带有四个碳环-离子基团烷基链接器）或苄基三甲基铵基团，在环和离子基团之间有亚甲基桥，通过可逆加成-断裂自由基（RAFT）聚合合成作为阴离子交换膜（AEM）。在相同条件下（IEC = 3.20 meq. g(-1)，水化数，λ = ∼7.0，由 DMF/1-丙醇（v/v = 3:1）铸膜，相对湿度 = 95%），与苄基三甲基铵样品（28.9 mS cm(-1))相比，C4 侧链聚合物的 Cl(-)电导率增加了 17%，达到 33.7 mS cm(-1)。如小角 X 射线散射（SAXS）所证实的，带有固定铵阳离子的侧链嵌段共聚物具有明确的层状形态，并与含有苄基三甲基铵的嵌段共聚物相比，相区间距显著减小。通过（1）H NMR 评估了嵌段共聚物在苛刻的加速条件下的化学稳定性，降解情况可见。在 1 M NaOD 水溶液中在 80°C 下 30 天的时间内，与基于苄基三甲基铵的 AEM 相比，带有 C4 侧链三甲基苯乙烯基丁基铵基序的嵌段共聚物显示出略微改善的稳定性。
