Physikalische Chemie, Universität Paderborn, 33098-D Paderborn, Germany.
Competence Center Analytics, BASF SE, 67056-D Ludwigshafen, Germany.
J Chem Phys. 2018 Mar 21;148(11):114906. doi: 10.1063/1.5019877.
Dilute solutions of sodium poly(styrene sulfonate) (NaPSS) in the presence of Al, Ca, and Ba were analysed by means of isothermal titration calorimetry (ITC) in order to investigate the heat effect of bond formation between those cations and the anionic SO residues of NaPSS. The selection of the cations was guided by the solution behavior of the corresponding PSS salts from a preceding study [M. Hansch et al., J. Chem. Phys. 148(1), 014901 (2018)], where bonds between Ba and anionic PSS showed an increasing solubility with decreasing temperature and Al exhibited the inverse trend. Unlike to Al and Ba, Ca is expected to behave as a purely electrostatically interacting bivalent cation and was thus included in the present study. Results from ITC satisfactorily succeeded to explain the temperature-dependent solution behavior of the salts with Al and Ba and confirmed the non-specific behavior of Ca. Additional ITC experiments with salts of Ca and Ba and sodium poly(acrylate) complemented the results on PSS by data from a chemically different polyanion. Availability of these joint sets of polyanion-cation combinations not only offers the chance to identify common features and subtle differences in the solution behavior of polyelectrolytes in the presence of multi-valent cations but also points to a new class of responsive materials.
在存在 Al、Ca 和 Ba 的情况下，通过等温滴定量热法（ITC）分析了聚（苯乙烯磺酸钠）（NaPSS）的稀溶液，以研究这些阳离子与 NaPSS 的阴离子 SO 残基之间形成键的热效应。阳离子的选择是根据先前研究中相应 PSS 盐的溶液行为指导的[M. Hansch 等人，J. Chem. Phys. 148(1), 014901 (2018)]，其中 Ba 与阴离子 PSS 之间的键表现出随着温度降低而溶解度增加的趋势，而 Al 则表现出相反的趋势。与 Al 和 Ba 不同，Ca 预计表现为纯静电相互作用的二价阳离子，因此包含在本研究中。ITC 的结果令人满意地成功解释了 Al 和 Ba 盐的温度依赖性溶液行为，并证实了 Ca 的非特异性行为。Ca 和 Ba 盐与聚（丙烯酸）的额外 ITC 实验通过来自化学上不同的聚阴离子的数据补充了 PSS 的结果。这些多价阳离子存在下的聚电解质溶液行为的共同特征和细微差异的识别机会，同时也指向了一类新的响应性材料。
