Preparation of layered double hydroxides intercalated with organic anions and their application in LDH/poly(butyl methacrylate) nanocomposites

Layered double hydroxides (LDHs) intercalated with monomer anions containing reactive vinyl group, namely acrylate, methacrylate (MA), 2-acrylamido-2-methyl-1-propanesulfonate (AMPS), and 4-vinyl-benzoate (VB), polymerization initiator, 4,4'-azobis(4-cyanopentanoate), and hydrophobizing agent, dodecyl sulphate (DS) were prepared by an anion exchange reaction, in which the coprecipitated Mg-Al-NO3 and Zn-Al-NO3 hydrotalcite-like compounds with M-II/Al molar ratio of 2 were used as precursors. The LDHs intercalated with MA, VB and DS anions were also prepared by direct coprecipitation. The intercalated LDHs were used as co-monomers or initiators for the preparation of LDH/poly(butyl methacrylate) nanocomposites; in situ emulsion polymerization and solution polymerization in 1-methyl-2-pyrolidone or the mixture of dimethylformamide and formamide were applied. Nanostructured hybrid materials containing a low amount (1-5 wt.%) of the inorganic filler were obtained; the best dispersion of LDH nanoparticles was observed in products prepared by solution polymerization in the mixture of dimethylformamide and formamide (50/50 v/v). Furthermore, the LDHs co-intercalated with monomer (MA or AMPS) and hydrophobic DS anions were prepared; at least a low amount of monomer anions has to be intercalated in the LDH interlayers in order to achieve an exfoliation of the ordered LDH structure. A modification of intercalated LDHs with porphyrin anions and the application of modified products in nanocomposite preparation were also examined. The photoactive LDH/poly(butyl methacrylate) nanocomposites producing singlet oxygen were obtained by this way. (C) 2009 Elsevier B.V. All rights reserved.