Synthesis of surface-modified monoclinic ZrO2 nanoparticles using supercritical water
Synthesis of surface-modified monoclinic ZrO2 nanoparticles using supercritical water
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我们采用超临界水热法成功简单快速地合成了表面修饰的单斜晶 ZrO2 纳米颗粒。将前体 Zr(OH)4 在各种带有羧基 (-COOH) 的表面改性剂存在下，在间歇式反应器中于 400 °C 下处理 10 分钟。油酸、癸二酸、十二烷二酸和12-氨基十二烷酸被用作表面改性剂。添加表面改性剂导致颗粒（微晶）尺寸比未改性的纳米颗粒更小，这表明表面改性剂和纳米颗粒之间存在相互作用。表面改性剂存在下粒径的减小归因于表面改性对晶体表面生长的抑制。 FT-IR 光谱显示，表面改性剂通过羧酸根 (-COO−) 和 Zr 离子之间的配位键附着在纳米粒子的表面。 FT-IR 光谱还证实了表面存在甲基 (–CH3)、羧基 (–COOH) 和胺 (–NH2) 等官能团。表面改性也通过热重分析得到验证。附着在产品表面的表面改性剂的数量为约2个分子/nm2。表面带有羧基和胺基官能团的纳米粒子具有水分散性；由于基团的性质，等电点转移到低 pH 范围。
We succeeded in simple and rapid synthesis of surface-modified monoclinic ZrO2 nanoparticles using a supercritical hydrothermal method. The precursor Zr(OH)4 was treated in the presence of various surface modifiers with carboxyl group (–COOH) in a batch-type reactor at 400 °C for 10 min. Oleic, sebacic, dodecanedioic, and 12-aminododecanoic acids were used as surface modifiers. Addition of surface modifiers resulted in smaller particle (crystallite) sizes than the unmodified nanoparticles, suggesting that there is an interaction between the surface modifiers and the nanoparticles. The reduced particle size in the presence of surface modifiers was attributed to the inhibition of the growth of the crystalline surface due to the surface modification. The FT-IR spectra revealed that the surface modifiers were attached to the surface of the nanoparticles through coordination bonds between the carboxylate group (–COO−) and the Zr ion. The FT-IR spectra also confirmed the presence of functional groups, such as methyl (–CH3), carboxyl (–COOH), and amine (–NH2), at the surface. The surface modification was also verified by the thermogravimetric analysis. The number of the surface modifiers attached to the surface of the products was about 2 molecules per nm2. The nanoparticles with carboxyl and amine surface functional groups were water dispersible; the isoelectric point shifted to low pH ranges because of the nature of the groups.