The shrinkage of sodium-poly(acrylate) PAA in divalent salt (strontium chloride (SrCl₂) and barium chloride (BaCl₂) solutions is investigated by atomistic molecular dynamics (MD) simulations to study the salt effect on PAA structure. The salt concentration (C_s) was varied in the range of 0 < C_s < 1 M for fully charged PAA. The PAA radius-of-gyration (R_g) decreases with C_s in the presence of both the divalent salts in qualitative agreement with experiments. The PAA chain stiffness calculated in persistence length (L_p) decreases over the entire range of C_s. At lower C_s, the PAA chains don't form aggregate, while at higher salt concentrations, PAA chains undergo self-association in both the divalent salts. The PAA-Water H-bonds decreases with C_s significantly in the presence of BaCl₂ as compared to SrCl₂. The PAA-Na⁺ radial distribution function (RDF) shows a decrease in its coordination number with C_s. The distribution of salt-ions around PAA shows that the Ba²⁺ condensation onto PAA is more significant than Sr²⁺ because of a greater coordination number for the former than the latter. Overall, the present study significantly advanced the molecular-level understanding of PAA microstructure in the dilute divalent metal salt solution.

_{通过原子分子动力学 (MD) 模拟研究了二价盐（氯化锶 (SrCl 2} ) 和氯化钡 (BaCl ₂ ) 溶液中的聚丙烯酸钠 PAA 的收缩，以研究盐对 PAA 结构的影响。盐浓度(C _s ) 对于完全充电的 PAA在 0 < C _{s < 1 M 的范围内变化。PAA 回转半径 (} R _g )在两种二价盐存在的情况下随 C _{s降低，与实验定性一致. 以持续长度 (L p} )计算的 PAA 链刚度在整个 C _s范围内减小。 在较低的 C _s，PAA 链不形成聚集体，而在较高的盐浓度下，PAA 链在两种二价盐中都发生自缔合。_{与 SrCl 2}相比，在 BaCl ₂存在下， PAA-水氢键随 C _s显着降低。PAA-Na ⁺径向分布函数 (RDF) 显示其与 C _s的配位数减少。PAA周围的盐离子分布表明Ba ^{2+在PAA上的凝聚比Sr 2+}更显着。因为前者的配位数比后者大。总体而言，本研究显着推进了对稀二价金属盐溶液中 PAA 微观结构的分子水平理解。