Synthesis and characterisation of exfoliated layered double hydroxide (LDH) / sugar nanocomposites

Swarnapali Indrasekara,Nilwala Kottegoda

doi:10.4038/jnsfsr.v39i2.3171

Abstract

Abstract : In this study the preparation of layered double hydroxide (LDH)/sugar nanocomposites using an exfoliated MgAl-lactate LDH (Mg: Al = 3:1) and a sugar (sucrose and maltose) as precursors is described. The products have been characterised by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The properties of the composite materials have been further studied using differential scanning calorimetry (DSC). The expanded interlayer spacing of the lactate LDH suggests the intercalation of lactate ions within the gallery region. Stirring of the MgAl-lactate LDH in water for 24 hours at room temperature resulted in a clear colloidal dispersion. Upon solvent evaporation, the resulting material consisted of a disorganized restacked LDH phase. The most significant evidence for the formation of nanocomposites from the exfoliated clay materials is suggested by the absence of reflections associated with the LDH in the PXRD patterns. DSC results suggest that the glass transition temperatures of the composite materials with 5%, 10% and 20% LDH loading are superior to the parent maltose. Therefore, the LDH nanolayers give the LDH filled sugar nanocomposites better thermal stability than the pristine sugar, thus these composites could be used as drug excipients in the pharmaceutical industry. Keywords : Amorphous sugar, exfoliation, layered double hydroxides, nanocomposites, thermal stability. Doi: 10.4038/jnsfsr.v39i2.3171 J.Natn.Sci.Foundation Sri Lanka 2011 39 (2): 113 - 119

Highlights

The expanded interlayer spacing of the lactate layered double hydroxide (LDH) suggests the intercalation of lactate ions within the gallery region
The patterns have been indexed based on a three layer repeating hexagonal unit cell, and the observed interlayer distances and the unit cell parameter c are summarised in Table 1. c-parameter has been calculated refering to the first two basal reflection (003) and (006) except for the carbonate LDH resulted after exfoliation and restacking
The observed pattern for lactate LDHs is in close agreement with that reported by Hibino and Kobayashi (Hibino & Kobayashi 2005)

Summary

Introduction

The expanded interlayer spacing of the lactate LDH suggests the intercalation of lactate ions within the gallery region. DSC results suggest that the glass transition temperatures of the composite materials with 5%, 10% and 20% LDH loading are superior to the parent maltose. Excipients make up the majority of the mass or volume of oral and parenteral drug products These pharmaceutical adjuvants, do not modify the intended action of the therapeutically active ingredients. Most of the drug excipients used in the pharmaceutical industry are crystalline solids, due to their high levels of purity and thermodynamic stablility. Some drug excipients such as polyvinylpyrolidine, cellulose and magnesium stearate, intrinsically exist in an amorphous form (Ahlneck & Zografi, 1990). Pharmaceutical products contain an active drug component together with agents that have a variety of purposes such as improving appearance and the

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Conclusion