Hybrid layer structure hydroxides

Different hybrid materials formed by insertion of organic polymers into inorganic substrates have been prepared. Layered materials are well known as host matrices for the incorporation of a large variety of polymeric organic species. Generally, the inorganic part is finely dispersed or exfoliated within the polymer, but, alternatively, the polymer can form laminae intercalated in laminar solids. This is the case for layered double hydroxides (LDHs, see Chapter 6), whose structure is closely related to that of the brucite, Mg(OH), in which the partial substitution of some of the divalent... 

The anionic interchange method involves the dispersion of LDH materials into a monomer solution, most often in aqueous mediiun (path 1 in Fig. 6) [52-54]. The dispersion is then stirred for several horns with mild heating. To be able to replace the interlayer anion, the monomer molecules should have such functionality as can stabilize the layered structure by neutralizing the excess charge on the hydroxide sheets of LDH. For example, acrylate anions are intercalated into Mg - Al LDH through ion exchange with Cl" or NO3" present in LDH. Lee and Chen reported intercalation of acrylate and 2-acryloamido-2-methyl propane sulfonate into hydrotalcite [51]. These intercalated hybrids are then dispersed in an alkah-neutralized solution of the monomer and the polymerization is carried out in the presence of an initiator. Leroux and coworkers prepared vinylbenzene sulfonate monomer intercalated Zn-Al LDH [52] and aminobenzene sulfonate monomer intercalated Cu-Cr LDH [53]. Further, Tanaka et al. reported acrylate ion intercalation within LDH by replacing the nitrate anion from Mg-Al LDH [54]. 

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