Synthesis, structure and morphology of organic layered double hydroxide (LDH) hybrids: Comparison between aliphatic anions and their oxygenated analogs

Intercalation of organic anions is an important aspect of layered double hydroxide (LDH) chemistry in the development of polymer LDH composites. In the research, we intercalated short and lengthy straight-chain organic anions with the carbon number up to 50 into the interlayer of MgAl and ZnAl-LDHs. We also noted that the packing mode of the straight-chain organic species and the basal spacing are somewhat predictable. In most cases, the hydrocarbon chain (or oxygenated) is packed in an anti-parallel inter-penetrating style at an angle of around 55 degrees. Only when the hydrocarbon chain contains 14-18 carbons and the supplied amount of the organic anion is more than the anion exchange capacity, a so-called bi-layer packing mode is also observed. Due to the variety in the structure and property of organic hydrocarbon chains, the organo-LDH crystallites show various morphologies, where the hydrophobic forces are expected to play an important role in determining the crystallite shape. (C) 2009 Elsevier B.V. All rights reserved.