Abstract
Polymer-clay nanocomposites are highly sought-after materials, mainly due to their applicability in a variety of avenues. From the standpoint of the preparation of these nanocomposites, however, organic compatibility with clay and adherence to “green chemistry” concepts and principles can be limiting factors. As such, the objective was to prepare a biopolymer-modified clay nanocomposite using a simple and environmentally friendly method of preparation, whereby pre-treatment of the clay for organic compatibility was bypassed. Novel montmorillonite nanocomposites were prepared using neutral guar gum and cationic guar gum. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of intercalated structures. A monolayer configuration of cationic guar within the interlayer space was indicated by XRD results, while treatment with neutral guar gum resulted in the observance of both monolayer and bilayer configurations. Additionally, TEM results indicated partial exfoliation. Results attributed from 13C cross polarization/magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS NMR) of the nanocomposites indicated peaks corresponding to the guar constituent, confirming the adsorption of the biopolymer. Inductively coupled plasma emission spectrometry (ICP-ES) results indicated the exchange of cations present in neutral guar gum with the sodium cations of montmorillonite, in the case of the neutral guar nanocomposites.
Highlights
Polymer layered silicates (PLS), an intensely researched class of nanocomposites, are the products of the association of polymers and layered silicates, forming a continuous phase containing a dispersed phase, with at least one dimension at the nanometer scale [1,2,3,4]
The X-ray diffraction (XRD) patterns of NG-MMT 3:1 (Figure 2C) and NG-MMT 6:1 (Figure 2D), as compared to the starting Na+ MMT (Figure 2A) revealed an enhancement of the d001 values, which indicated the intercalation of neutral guar gum within the montmorillonite layers
Novel guar-montmorillonite nanocomposites were prepared by the solution intercalation method
Summary
Polymer layered silicates (PLS), an intensely researched class of nanocomposites, are the products of the association of polymers and layered silicates, forming a continuous phase containing a dispersed phase, with at least one dimension at the nanometer scale [1,2,3,4]. The impetus towards natural polysaccharide-modified clay is based on the general biodegradability, environmental friendliness and renewable nature of these biopolymers [19,20], which is in accordance with the concept of green nanocomposites [21]. Guar gum is a good candidate to modify montmorillonite for potential pharmaceutical applications. Its intercalation would increase the interlayer space of montmorillonite which can potentially effectuate the further intercalation of other organic molecules [31] for example, drug molecules for pharmaceutically interesting applications. Along with increasing the interlayer space, the intercalated guar gum contains many hydroxyl groups, which may allow interactions to occur with drug molecules, potentially encouraging the uptake of drug compounds by montmorillonite. NMR) spectroscopy, and inductively coupled plasma emission spectrometry (ICP-ES) were used for characterization purposes
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