Tailoring the Third Dimension of Layered Double Hydroxides
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Layered double hydroxides (LDHs) have attracted lots of attention in the research field for their controllable composition and gallery spacing. LDHs have been used as catalysts, anion exchange materials, fire retardants and in polymer nanocomposites. Exfoliating LDHs into single layers nanosheets, can make the most use of the layers. New physical properties under nanoscale make new inventions of multifunctional materials possible. Different approaches to delaminate LDHs were reviewed in this thesis. Yet, none of the reported methods to obtain 2-D LDHs nanosheets was efficient. Herein, we report a new methodology to directly synthesize LDHs nanosheets. Mg/Al-LDHs nanosheets were synthesized in the presence of 23% formamide via a titration method. Formamide was used as an inhibitor that prevents the growth of LDHs in the Z-direction. LDHs/polymer nanocomposites have been extensively studied. Various methods to prepare LDHs nanocomposites have been developed. In situ intercalation of polyelectrolytes into LDHs has been reported. However, the exclusion of CO2 is a requirement during the process. Herein, we report a new approach to prepare LDHs/polyelectrolyte intercalation compounds via an in situ intercalation method. The LDH was synthesized in the presence of a polyelectrolyte [poly(sodium 4-styrene-sulfonate) (PSSS) or poly(acrylic acid, sodium) (PAAS)] by a urea hydrolysis method. Characterization data confirmed the successful intercalation. The intercalated polyelectrolytes turned to be more thermally stable as confirmed by the TGA data.