In this work, the effect of using zirconium(IV) hydroxide (Zr(OH)₄) nanoparticles in the enhancement of the thermal stability and viscoelastic properties of organically cross-linked polyacrylamide (PAM) hydrogels using hydroquinone (HQ) and hexamethylenetetramine (HMT) was studied. The thermal stability and viscoelastic properties of the PAM gels were studied by DSC and DMA, respectively. From the DSC analysis, the bound and free water contents were analyzed along with the degradation enthalpy to give a preliminary clue about the direct vs indirect interactions taking place in the gel. With the addition of 0.2–0.8 wt % Zr(OH)₄, the thermal stability of the PAM hydrogel improved by 3–5 °C (reaching 187 °C) compared to PAM alone. Moreover, the elasticity of the PAM hydrogel increased with the addition of Zr(OH)₄ which was also supported by the strong interaction bond formed as demonstrated from the higher degradation enthalpy and free water recorded. These interactions were further explained using FTIR and optical microscope images. The TGA results also revealed the functionalization of PAM gel and showed that the gel was thermally stable even at 400 °C. In addition, the effects of calcination, organic cross-linker, salinity, and pH on the gel properties were investigated. From DSC and DMA analysis, it was found that the optimal conditions for the polymer gel were as follows: PAM at 4 wt %, Zr(OH)₄ at 0.2–0.8 wt %, organic cross-linkers (OrgCL) at 0.3 wt %, and KCl or MgCl₂ at 2 wt %.

中文翻译：

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使用氢氧化锆纳米粒子在高温下关闭水的增强聚丙烯酰胺聚合物凝胶：热和流变学研究

在这项工作中，使用氢氧化锆（IV）（Zr（OH）₄）纳米颗粒增强了使用氢醌（HQ）和六亚甲基四胺（HMT）的有机交联聚丙烯酰胺（PAM）水凝胶的热稳定性和粘弹性。 ）进行了研究。通过DSC和DMA分别研究了PAM凝胶的热稳定性和粘弹性。通过DSC分析，分析了结合水和游离水的含量以及降解焓，从而给出了有关凝胶中直接相互作用与间接相互作用的初步线索。加入0.2–0.8 wt％的Zr（OH）₄与单独使用PAM相比，PAM水凝胶的热稳定性提高了3-5°C（达到187°C）。此外，PAM水凝胶的弹性随着Zr（OH）₄的添加而增加，Zr（OH）₄也受到形成的强相互作用键的支持，这由较高的降解焓和记录的游离水证明。使用FTIR和光学显微镜图像进一步解释了这些相互作用。TGA结果还揭示了PAM凝胶的功能化，并表明该凝胶即使在400°C时也具有热稳定性。另外，研究了煅烧，有机交联剂，盐度和pH对凝胶性质的影响。通过DSC和DMA分析，发现聚合物凝胶的最佳条件如下：PAM为4重量％，Zr（OH）₄在0.2–0.8 wt％的范围内，有机交联剂（OrgCL）在0.3 wt％的范围内，而KCl或MgCl ₂在2 wt％的范围内。