The bioactive agents p-hydroxymethylbenzoate, 2,4-dihydroxymethylbenzoate and methylsalicylate were reacted with polyoxyalkylene (D 230 -2000 )-montmorillonite (MMT) intercalated nanocomposites. D 230 -2000 -MMT were prepared by an ion exchange process of Na-MMT and-NH 3 + groups in polyoxyalkylene amine hydrochloride of three different molecular masses (D 230 , D 400 and D 2000 ). The results of X-ray analysis and transmission electron microscopy show that D 2000 -MMT/phydroxymethylbenzoate is an exfoliated nanocomposite, whereas in D 230 -MMT/p-hydroxymethylbenzoate, D 230 -MMT/2,4dihydroxymethylbenzoate, D 230 -MMT/methylsalicylate and D 400 -MMT/p-hydroxymethylbenzoate, having lower molecular mass and polymer loading, the MMT rearranges in an intercalated and flocculated structure. The amount of intercalated polymer and interaction between polymer and layered silicate were determined using thermogravimetric analysis and Infrared spectroscopy. The antimicrobial activities of the nanocomposites were qualitatively and quantitatively assessed by agar diffusion tests and minimal inhibitory concentration values against a Gram-negative bacterium (Escherichia coli NCIM 2065), a Gram-positive bacterium (Bacillus subtilis ATCC) and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D 2000 -MMT/p-hydroxymethylbenzoate nanocomposite strongly inhibits the growth of all the micro-organisms tested. The diameter of the inhibition zone varies according to the type of micro-organism tested. The effect of nanocomposite concentration on morphology, respiration and release of calcium, potassium and sodium ions of the test micro-organisms was examined.

Vanillin (4‐hydroxy‐3‐methoxy benzaldehyde) and 5‐formylamino salicylic acid microbicides were reacted with polyoxyalkylene‐montmorillonite (D230–2000‐MMT) nanocomposites. The microstructure of these Schiff base nanocomposites was characterized by TEM and XRD. D230–2000‐MMT nanocomposites were prepared by an ion exchange process of sodium montmorillonite (Na‐MMT) and NH3 + groups in polyoxyalkylene amine hydrochloride with three different molecular masses of D230, D400, and D2000. Wide‐angle X‐ray diffraction confirms the intercalation of the polymer between the silicate layers. Electrostatic interaction between the positively charged NH3 + groups and the negatively charged surface of MMT was observed. The nanocomposites were tested for antimicrobial activity against the Gram‐negative bacteria (Escherichia coli NCIM 2065), Gram‐positive bacteria (Bacillus subtillus ATCC), and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D2000‐MMT/vanillin Schiff base nanocomposite strongly inhibited the growth of all microorganisms that can be used in different applications. The amount of loaded polymer and the structure of the nanocomposite play an important role in inhibiting the bacterial and fungal strains. It is found that the Schiff base nanocomposite affect the morphology, oxygen consumption, and the release of cytoplasmic constituents such as potassium (K+), sodium (Na+), and calcium (Ca2+) ions leading to death of the cells. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers