Polyelectrolyte-based conductive hydrogels are being extensively explored for applications in energy storage and as electrode materials for batteries. We synthesized ionically crosslinked sodium carboxymethyl cellulose (NaCMC), esterified NaCMC, and Ca doped esterified NaCMC hydrogels. This work aims to understand the effect of Ca ions on the NaCMC and esterified NaCMC. FTIR, SEM, Rheology and EIS studies were performed to understand the structure and dynamics of hydrogels. Results confirmed that Ca ions have an important role in determining the rheological and dielectric response of hydrogels. Power law behavior was observed in their rheological response with exponent (n) of 0.81 for G′ and 0.76 for G″ of ionically crosslinked NaCMC, 5.38 for G′ and 4.70 for G″ of esterified NaCMC, whereas, negative exponents −1.44 for G′ and −1.10 for G″ of Ca ion doped esterified NaCMC. Ionically crosslinked NaCMC hydrogels have relaxation times () in the range of 8.9 10 s–2.8 10 s may be due to the formation of temporary dipoles by electrostatic bridge formations with dc conductivity of (0.1 S/cm–5 S/cm), whereas, esterified NaCMC showed relaxation times (10 s–8.9 10 s) with increasing ester crosslinks and dc conductivity of (0.05 S/cm–0.8 S/cm). Interestingly, Ca ion doped esterified hydrogels showed multiple dielectric relaxations on Ca ion addition with different relaxation times may be due to change in ionic environment. The understanding obtained from this work may be useful for designing tuneable hydrogels with optimum electrical and mechanical properties.

中文翻译：

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羧甲基纤维素钠 (NaCMC)/Ca2+ 和酯化 NaCMC/Ca2+ 水凝胶的流变学和介电行为：将微观结构和动力学与性能相关联

基于聚电解质的导电水凝胶正在被广泛探索在储能和电池电极材料中的应用。我们合成了离子交联羧甲基纤维素钠（NaCMC）、酯化NaCMC和Ca掺杂酯化NaCMC水凝胶。本工作旨在了解 Ca 离子对 NaCMC 和酯化 NaCMC 的影响。进行 FTIR、SEM、流变学和 EIS 研究以了解水凝胶的结构和动力学。结果证实，Ca 离子在决定水凝胶的流变学和介电响应方面具有重要作用。在其流变响应中观察到幂律行为，离子交联的 NaCMC 的 G' 的指数 (n) 为 0.81，G'' 的指数 (n) 为 0.76，酯化 NaCMC 的 G' 的指数 (n) 为 5.38，G'' 的指数 (n) 4.70，而 G 的指数为负指数 -1.44 Ca离子掺杂的酯化NaCMC的G”为'和-1.10。离子交联的 NaCMC 水凝胶的弛豫时间 () 在 8.9 10 s–2.8 10 s 范围内，可能是由于静电桥形成的临时偶极子的形成，直流电导率为 (0.1 S/cm–5 S/cm)，而，酯化的NaCMC随着酯交联的增加和直流电导率（0.05 S/cm-0.8 S/cm）的增加而表现出弛豫时间（10 s–8.9 10 s）。有趣的是，Ca离子掺杂的酯化水凝胶在Ca离子添加时表现出多种介电弛豫，不同的弛豫时间可能是由于离子环境的变化所致。从这项工作中获得的理解可能有助于设计具有最佳电气和机械性能的可调节水凝胶。