Synthesis and Studies on Surface Active Water Soluble Derivatives of Siloxane Oligomers

Abstract

We report the synthesis of cationic water-soluble siloxanes by reacting aminosiloxanes with dimethyl, n-dodecyl 3-chloro-2-hy-droxypropyl quaternary ammonium iodide (DDCQA). Tetramethyl disiloxane on hydrosilation with allyl amine in the presence of hex-achloroplatinic acid/IPA gave bis(3-aminopropyl) octamethyltetra-siloxane. In addition, formation of Si-H containing oligomeric siloxanes were detected during this reaction and the extent of formation of the oligomers was found to depend upon the concentration of platinum. The oligomerization reaction was explained by dehydrogenative coupling of Si-H groups in the presence of platinum catalyst. A plausible mechanism for formation of aminosiloxane and the Si-H oligomers were proposed. Alternatively, cyclic Si -H containing siloxanes on polymerization using butyl lithium gave oligomeric Si-H containing siloxanes, which were hydrosilated to give aminosiloxanes. The quaternary aminosiloxanes synthesized showed lowering in surface tension of water to 26 mN/m.