Binding interaction and gelation in aqueous mixtures of poly(N-isopropylacrylamide) and hectorite clay.
Binding interaction and gelation in aqueous mixtures of poly(N-isopropylacrylamide) and hectorite clay.
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DOI：
10.1021/jp510526j
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发表时间：
2015-01
期刊：
影响因子：
--
通讯作者：
Cuixia Lian;Enzhong Zhang;Tao Wang;Weixiang Sun;Xinxing Liu;Zhen Tong
中科院分区：
文献类型：
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作者：
Cuixia Lian;Enzhong Zhang;Tao Wang;Weixiang Sun;Xinxing Liu;Zhen Tong
为探讨在粘土悬浮液中原位聚合聚N-异丙基丙烯酰胺(PNIPAM)的强纳米复合水凝胶(NC Gel)的交联机理，用石英晶体耗散微天平(QCM-D)直接检测了PNIPAM链与粘土颗粒之间的结合作用。PNIPAM链被允许吸附在QCM电极的金表面。当引入粘土时，准共振膜中有较大的频移Δf，这表明沉积的PNIPAM层上吸附了大量的粘土小片。耗散位移ΔD与Δf之间的关系表明，粘土片的吸附经历了快速初始堆积和随后的致密化两个阶段。从流体力学直径观察，在稀水混合物中，PNIPAM链与粘土形成聚集体。建立了浓水PNIPAM-粘土混合物的凝胶态图。拉曼光谱表明，当粘土加入到水溶液中时，PNIPAM链的构象发生了变化，这可能是由于PNIPAM链吸附在粘土小片上而引起的。
The binding interaction between poly(N-isopropylacrylamide) (PNIPAm) chains and hectorite clay platelets was directly detected by quartz crystal microbalance with dissipation (QCM-D) to explore the cross-linking mechanism in the strong nanocomposite hydrogel (NC gel), which is in situ polymerized with NIPAm in the clay suspension. PNIPAm chains were allowed to be adsorbed on the gold surface of the QCM electrode. A large frequency shift Δf in the QCM as introducing the clay indicated that a large amount of clay platelets were adsorbed on the deposited PNIPAm layer. The relationship between the dissipation shift ΔD and Δf revealed that the adsorption included two steps of fast initial buildup and following densification of the clay platelets. In dilute aqueous mixtures, the PNIPAm chain and clay formed aggregates as observed from the hydrodynamic diameter. A gelation state diagram was established for concentrated aqueous PNIPAm-clay mixtures. The Raman spectrum pointed out the conformation change of the PNIPAm chains in aqueous solutions when the clay was added, which would be caused by the adsorption of PNIPAm chains to the clay platelets.