w-十一烯酸表面改性纳米碳酸钙粒子反应机理的差示FTIR光谱研究

Study on the Reaction Mechanism of Surface Modified Nano-CaCO_3 Particles Using w-Undecenoic Acids as Modifier by FTIR Difference Spectroscopy

采用差示傅里叶变换红外光谱(FTIR)法对w-十一烯酸表面改性的纳米碳酸钙粒子的组成进行了测试,结果发现:在其差谱上,波数位于1 572,1 542 cm-1附近出现了较明显的(RCOO)2-Ca离子的特征吸收带,波数位于912,3 078 cm-1附近分别出现了端双键上C—H的面外弯曲(γCH)和伸缩振动(νCH)吸收带,波数位于1 746,1 703 cm-1附近分别出现了酯羰基和羧羰基的特征吸收带。由此推测,改性剂与纳米碳酸钙表面作用机理可能是:改性剂的端羧基与纳米碳酸钙表面的钙离子结合,形成(RCOO)2-Ca离子键,从而在纳米碳酸钙表面接枝上带有端双键的活性有机基团;同时,纳米碳酸钙表面利用氢键作用吸附微量有机基团。这些有机基团共同缠绕在纳米碳酸钙表面,提高了纳米碳酸钙在无水乙醇中的分散性。

The components of the surface modified nanometer calcium carbonate particles with w-undecenoic acids as modifier were tested by differential FTIR spectroscopy. Some special absorption bands respectively assigned to （RCOO）2-Ca,γ c=cu , vc=cu , vRCOOR, vRCOOH at the wavenumbers of 1 572, 1 542, 912, 3 078 cm^-1, 1 746 and 1 703 cm^-1 were found. The possible modification mechanisms is that the organic acid reacts with the exposed Ca^2＋ of the nano-CaCOa surface to form ion-bond （RCOO）2Ca; and the other organic groups are absorbed onto the surface of nano-CaCOa by hydrogen-bond. These organic groups twist on the surface of nano-CaCOa particles. So the dispersion of the modified nano-CaCOa particles is increased remarkably in absolute ethanol.