Menceloğlu Yeşim, Menceloğlu Yusuf Ziya, Seven Senem Avaz
Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, 34956 Istanbul, Turkey.
Sabanci University Integrated Manufacturing Technologies Research and Application Center & Composite Technologies Center of Excellence, Teknopark, Pendik, 34906 Istanbul, Turkey.
ACS Omega. 2022 Jun 8;7(24):20486-20494. doi: 10.1021/acsomega.1c06961. eCollection 2022 Jun 21.
Superabsorbent polymers (SAPs) are useful polymers in a wide range of application fields ranging from the hygiene industry to construction and agriculture. As versatility and high water absorption capacity are their important merits, SAPs usually suffer from low water retention capacity (fast release) and weak mechanical properties. To address these drawbacks, a set of new superabsorbent polymer-Halloysite nanotube (HNT) nanocomposites was synthesized via free radical polymerization of acrylamide, 2-acrylamido-2-methylpropane-1-sulfonic acid, and acrylic acid in the presence of vinyltrimethoxysilane (VTMS) as the crosslinker. FTIR and TGA characterizations confirm the polymerization of SAP and successful incorporation of HNTs into the SAP polymer matrix. The effect of the HNT nanofiller amount in the nanocomposite polymer matrix was investigated with swelling-release performance tests, crosslink density calculations, and rheology measurements. It was found that equilibrium swelling ratios are correlated and therefore can be tuned via the crosslink densities of nanocomposites, while water retention capacities are governed by storage moduli. A maximum swelling of 537 g/g was observed when 5 wt % HNT was incorporated, in which the crosslink density is the lowest. Among the SAP nanocomposites prepared, the highest storage modulus was observed when 1 wt % of nanofiller was incorporated, which coincides with the nanocomposite with the longest water retention. The water release duration of SAPs was prolonged up to 27 days with 1% HNT addition in parallel with the achieved maximum storage modulus. Finally, three different incorporation mechanisms of the HNT nanofiller into the SAP nanocomposite structure were proposed and confirmed with rheology measurements. This study provides a rapid synthesis method for SAP nanocomposites with enhanced water retention capacities and explains the relationship between swelling and crosslink density and water retention and mechanical properties of SAP nanocomposites.
高吸水性聚合物（SAPs）是一类用途广泛的聚合物，应用领域涵盖卫生行业、建筑和农业等。由于具有多功能性和高吸水性这两个重要优点，SAPs通常存在保水能力低（快速释放）和机械性能弱的问题。为了解决这些缺点，通过在作为交联剂的乙烯基三甲氧基硅烷（VTMS）存在下，使丙烯酰胺、2-丙烯酰胺基-2-甲基丙烷-1-磺酸和丙烯酸进行自由基聚合，合成了一组新型的高吸水性聚合物-埃洛石纳米管（HNT）纳米复合材料。傅里叶变换红外光谱（FTIR）和热重分析（TGA）表征证实了SAP的聚合以及HNTs成功掺入到SAP聚合物基体中。通过溶胀-释放性能测试、交联密度计算和流变学测量，研究了纳米复合聚合物基体中HNT纳米填料含量的影响。结果发现，平衡溶胀率是相关的，因此可以通过纳米复合材料的交联密度进行调节，而保水能力则由储能模量决定。当掺入5 wt%的HNT时，观察到最大溶胀度为537 g/g，此时交联密度最低。在所制备的SAP纳米复合材料中，当掺入1 wt%的纳米填料时，观察到最高的储能模量，这与保水时间最长的纳米复合材料相吻合。添加1%的HNT可使SAPs的水释放持续时间延长至27天，同时实现了最大储能模量。最后，提出了HNT纳米填料掺入SAP纳米复合结构的三种不同机制，并通过流变学测量得到证实。本研究提供了一种快速合成具有增强保水能力的SAP纳米复合材料的方法，并解释了SAP纳米复合材料的溶胀与交联密度以及保水与机械性能之间的关系。
