Scholarlink

<p>Polyacrylic acid (PAA) and polyacrylamide (PAM), two synthetic superabsorbent polymers (SAPs) commonly used, inter alia, in agriculture, can form three‑dimensional hydrogels that enhance soil water retention and soil structural stability. Yet, their potential aging and transformation under natural drying-rewetting dynamics and in contact with soil solutes remain unclear. In this study, we examined the effect of soil extracts from sand, loam, and clay soil in both a 72&#xa0;h free swelling experiment (FSE) and in an incubation experiment (IE), where PAA and PAM hydrogels underwent ten successive drying-rewetting cycles. Samples were taken after cycles 0, 3, 5, and 10 and investigated for their swelling index (SI), water entrapment (<sup>1</sup>H proton nuclear magnetic resonance relaxometry), structural stability (rheometry), morphology (scanning electron microscopy), and surface chemistry (fourier transform infrared spectroscopy). In the FSE, PAA swelling in all soil extracts reduced SI, shortened T₂ relaxation, and increased solid-like characteristics, whereas PAM properties remained stable except when swollen in sand extract. During the IE, PAA exhibited progressive hydrogel network densification, further SI loss, T<sub>2WL</sub> shortening, band intensity shifts, and microstructural densification, whereas PAM remained largely inert. Multivariate analysis confirmed that polymer identity and its interaction with the conducted drying-rewetting cycles and soil extract composition drove SAP aging. Overall, drying-rewetting cycles appear to induce irreversible chemo-structural alterations in anionic PAA, reducing its rehydration potential and promoting persistent, solid, plastic-like residues. In contrast, neutral PAM was more resilient under dynamic environmental conditions.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

The contribution of soil extract composition and cyclic moisture dynamics to the physicochemical aging of superabsorbent polyacrylic acid and polyacrylamide hydrogels

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年5月22日

查看全文
  • Janina Neff,
  • Christian Buchmann

摘要

Polyacrylic acid (PAA) and polyacrylamide (PAM), two synthetic superabsorbent polymers (SAPs) commonly used, inter alia, in agriculture, can form three‑dimensional hydrogels that enhance soil water retention and soil structural stability. Yet, their potential aging and transformation under natural drying-rewetting dynamics and in contact with soil solutes remain unclear. In this study, we examined the effect of soil extracts from sand, loam, and clay soil in both a 72 h free swelling experiment (FSE) and in an incubation experiment (IE), where PAA and PAM hydrogels underwent ten successive drying-rewetting cycles. Samples were taken after cycles 0, 3, 5, and 10 and investigated for their swelling index (SI), water entrapment (1H proton nuclear magnetic resonance relaxometry), structural stability (rheometry), morphology (scanning electron microscopy), and surface chemistry (fourier transform infrared spectroscopy). In the FSE, PAA swelling in all soil extracts reduced SI, shortened T₂ relaxation, and increased solid-like characteristics, whereas PAM properties remained stable except when swollen in sand extract. During the IE, PAA exhibited progressive hydrogel network densification, further SI loss, T2WL shortening, band intensity shifts, and microstructural densification, whereas PAM remained largely inert. Multivariate analysis confirmed that polymer identity and its interaction with the conducted drying-rewetting cycles and soil extract composition drove SAP aging. Overall, drying-rewetting cycles appear to induce irreversible chemo-structural alterations in anionic PAA, reducing its rehydration potential and promoting persistent, solid, plastic-like residues. In contrast, neutral PAM was more resilient under dynamic environmental conditions.