Novel bionanocomposites of poly(vinyl alcohol) and modified chiral layered double hydroxides: Synthesis, properties and a morphological study

The effect of novel modified layered double hydroxides (LDHs) on thermal and structural properties of poly(vinyl alcohol) (PVA) was investigated. Organically modified chiral LDH was prepared via ion exchange reaction of LDH in a solution of N,N'-(pyromellitoyl)-bis-L-phenyialanine diacid in distilled water. The modified Mg-Al LDH materials showed an increase in interlayer distance as compared to the unmodified Mg-Al LDH by X-ray diffraction (XRD). Bionanocomposites of PVA with the modified chiral LDH were prepared with different compositions of LDH by solution-intercalation method using the ultrasound-assisted technique. The effect of LDH contents on thermal, physicomechanical, and morphological properties of PVA films was investigated using XRD, Fourier transform infrared, thermogravimetric analysis (TGA), field emission scanning electron microscopy and transmission electron microscopy techniques. The TGA of the obtained bionanocomposites showed an increase in thermal stability. The uniform distribution of clay due to the intimate interaction between clay and polymer appeared to be the reason for the improved properties. (C) 2013 Elsevier B.V. All rights reserved.