Polysilsesquioxanes and oligosilsesquioxanes substituted by alkylammonium salts as antibacterial biocides

Octa(3-chloropropylsilsesquioxane), (T-ClPr)(8), and a soluble, low molecular weight, poly(3-chloropropylsilsesquioxane) were subjected to a reaction with dimethyl-n-octylamine to convert part or almost all the chloropropyl groups to corresponding quaternary ammonium salt (QAS) groups. Polysilsesquioxanes containing secondary n-amylammonium salt (SAS) groups were synthesized by reaction of n-alkyl bromides with poly(3-aminopropylsilsesquioxane) of limited molecular weight or by amination of n-amyl bromide with 3-aminopropyltriethoxysilane followed by hydrolysis and polycondensation. The antibacterial activity of these QAS- and SAS-containing silsesquioxane materials against two representative Gram-positive and three representative Gram-negative bacterium strains were tested. Most of these materials showed high or moderate activity against Gram-positive bacteria and moderate or weak activity against Gram-negative bacteria.