Synthesis and antimicrobial activity of biocidal polymer-montmorillonite nanocomposites

The bioactive agents p-hydroxymethylbenzoate, 2,4-dihydroxymethylbenzoate and methylsalicylate were reacted with polyoxyalkylene (D2302000)montmorillonite (MMT) intercalated nanocomposites. D2302000MMT were prepared by an ion exchange process of Na-MMT and?NH3+ groups in polyoxyalkylene amine hydrochloride of three different molecular masses (D230, D400 and D2000). The results of X-ray analysis and transmission electron microscopy show that D2000MMT/p-hydroxymethylbenzoate is an exfoliated nanocomposite, whereas in D230MMT/p-hydroxymethylbenzoate, D230MMT/2,4-dihydroxymethylbenzoate, D230MMT/methylsalicylate and D400MMT/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 D2000MMT/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. Copyright (C) 2011 Society of Chemical Industry