Quantification and key factors in delamination of (Mg1 − yNiy)1 − xAlx(OH)2(NO3)x·mH2O

Abstract

Dispersions of delaminated layered double hydroxides (LDH) contain nanosheets of interest for single particle studies and for preparation of different types of clay mineral-clay mineral or clay mineral–polymer nanocomposites and coatings. Reproducible methods were currently benchmarked, key parameters influencing the degree of delamination were identified, and prerequisites for achieving high yield delamination routes evaluated. Inert synthesis, screening by turbidity measurements and gravimetric quantification allowed identification of how various parameters influence delamination. For (Mg1−yNiy)1−xAlx(OH)2(NO3)x·mH2O preparative parameters as hydrothermal treatment, drying conditions and pH during synthesis have significant impact on delamination abilities. Poorly delaminating Ni0.75Al0.25(OH)2(NO3)0.25·mH2O LDH is by adequate hydrothermal treatment converted to a material that undergoes almost complete delamination. The adopted procedures allow systematic studies on how preparative parameters as well as more chemical parameters such as interlayer chemistry and cationic composition in the brucite like layers interacts with solvent properties. Improved insight into parameters controlling delamination properties open up for routes on large scale manufacturing of clay mineral-clay mineral nanocomposites requested for novel types of catalysts. Particles, dispersions and nanosheets were characterized by ICP-OES, CN-analysis, turbidity, XRD, TEM, SAXS, AFM and XPS measurements.