Dispersion of Organically Modified Layered Silicates in Melt Blended Poly(Lactic Acid) Composites: Effects of Cation Head Groups and Oxygenated Alkyl Chains

Abstract

Extruded organically modified layered silicate (OMLS) -poly(lactic acid) (PLA) composites exhibit a mixed intercalated/exfoliated morphology.To explore effects of surfactant hydrophobicity and polarity on the quality of dispersion, a series of OMLS were prepared from quaternary ammonium, phosphonium, and imidazolium salts, including some synthesized hexadecanoic acid containing ionic liquids. The alkyl chains were modified to include aromatic and oxygen moieties while keeping the same long alkyl chain length. Nile Blue was co-exchanged to add a fluorescent tag to the layered silicates. The effectiveness of this technique for PLA and different Nile Blue salts were assessed. Degree of exfoliation was monitored using x-ray diffraction and fluorescence spectroscopy. Thermal characteristics of the new OMLS were measured.