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新方法合成规则六角片状层状双金属氢氧化物

齐凤林,张晓晴,李淑萍*   

  1. (江苏省生物功能材料重点实验室， 南京师范大学化学与材料科学学院 南京 210097)
  • 收稿日期:2012-09-07 修回日期:2012-11-21 出版日期:2013-07-10 发布日期:2013-07-10
  • 通讯作者: 李淑萍，教授; Tel:025-83598280; Fax:025-83598287; E-mail:lishuping@njnu.edu.cn; 研究方向：胶体与界面化学以及药物载体
  • 基金资助:
    国家自然科学基金(21073093)高等学校博士点专项科研基金(20103207120006)和江苏高校优势学科建设工程资助项目

Preparation of Layered Double Hydroxides with Regularly Hexagonal Morphology

QI Fenglin, ZHANG Xiaoqing, LI Shuping*   

  1. (Jiangsu Key Laboratory of Biofunctional Materials,College of Chemistry and Materials
    Science,Nanjing Normal University,Nanjing 210097,China)
  • Received:2012-09-07 Revised:2012-11-21 Published:2013-07-10 Online:2013-07-10

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1964

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2

摘要： 探索了一种合成规则的层状双金属氢氧化物(简称LDHs)六角纳米片的新方法，该方法基于传统的共沉淀法，并借鉴了尿素法的优点。 系统研究了沉淀剂、反应溶剂、反应时间和沉淀剂滴加速率对最终得到的粒子结晶度和形貌的影响。 研究结果表明，采用NH4OH为沉淀剂，以乙醇/水混合溶液为溶剂得到的LDHs纳米粒子结晶度高，晶型发育完美，呈现规则的六角片状，单分散性良好，粒径介于100~250 nm之间。 乙醇的加入一方面减慢了NH4OH电离出OH-的速率，降低了溶液过饱和度；另一方面，乙醇分子包裹在LDHs粒子周围，其表面的羟基起到了空间位阻作用，阻止粒子之间的团聚。 最佳反应时间既要保证LDHs晶粒的充分发育和成长，又要防止粒子之间的团聚。反应时间较短(1 h)时，晶粒发育不完全，粒子呈现不规则的六角片形；反应时间较长(4 h)时，LDHs粒子出现了六角片状重叠现象；只有当反应时间适中(3 h)，LDHs粒子因晶胞生长充分而粒径分布均匀，并呈现规则六角片状。 沉淀剂滴加速率的不同会改变体系的过饱和度，从而影响LDHs粒子的形貌，滴加速率较低(0.025 mL/s)时，得到的粒子形貌规则、单分散性良好，且随着滴加速率的降低，粒子粒径逐渐增大。

关键词: 纳米粒子, 层状化合物, 层状双金属氢氧化物, 六角片状

Abstract: A new synthetic approach based on the co-precipitation method was explored to synthesize regularly hexagonal Mg-Al-NO3-LDHs nanoparticles by taking the advantages of the conventional urea hydrolysis method. The effects of precipitator, solvent, reaction time and the dropping speed of precipitator on the crystallinity and morphologies of LDHs were systematically studied. Nearly monodispersed and regularly hexagonal morphology of LDHs with high crystallinity and particle size in the range of 100~250 nm could be obtained using NH4OH as precipitator and a mixture of alcohol and water as solvent. The addition of alcohol might slow down the ionization rate of NH4OH into OH- and benefit the reduction of the supersaturation degree. In addition, the alcohol could be absorbed on the surface of LDHs particles and the hydroxyl groups play a steric repulsion effect, which prevent the aggregation of the particles. Our results also show that an incomplete particle growth occurred at short reaction time(1 h) will lead to the formation of irregular and hexagonal particles, while the aggregation of particles tends to take place when the reactions are prolonged(4 h). Furthermore, the effect of dropping speed of precipitators was also investigated. A low dropping speed(0.025 mL/s) of precipitator favors the formation of regularly hexagonal particles with good monodispersity, and the particle size increases with the decrement of dropping speed.

Key words: nanoparticles, layered compouds, layered double hydroxides, hexagonal

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