Novel modifiers for layered double hydroxides and their effects on the properties of polylactic acid composites

Hydrophobic modification of a carbonated layered double hydroxide (LDH) and its calcined equivalent was conducted by direct ion exchange reactions with three ionic liquids having the same phosphonium-based cation, but different anions. Among the ionic liquids, successful anionic intercalation was only carried out when calcined LDH reacted with a phosphinate anion containing ionic liquid, in excess of the stoichiometric amount. Ionic liquids containing a linear decanoate anion or the least bulky PF6 anion promoted the formation of a surface coating rather than increase of the interlayer space as confirmed by X-ray Diffraction, Infrared Spectroscopy, and Thermogravimetric analysis. The intercalated LDH was found to minimize the plasticizing/degradative effect of the ionic liquid on a polylactic acid PLA matrix and could be used as reservoir for the controlled release of the phosphorous containing anions for antibacterial or similar applications.