Surface activity and water repellency properties of cleavable-modified silicone surfactants

A series of cleavable water-soluble silicone surfactants were prepared by the reaction of a hydroxyl-terminated polyester and an organopolysiloxane. Cleavable surfactants can decompose into water-insoluble moiety of silanol and two water-soluble products under acidic conditions, whereas these compounds are stable under neutral or alkaline conditions. The structure change of theses cleavage products are confirmed by IR and UV spectra analysis. The fundamental surface activity including surface tension, foaming, contact angle and viscosity are studied. The photocatalytic degradation of modified silicone surfactants with UV light over titanium oxide was investigated. Experimental results have confirmed that products are slowly degraded by direct photolysis. However, the cleavable silicone surfactant was easily photocatalytically degraded with UV irradiation in the presence of TiO2. Addition of TiO2 to the reaction system substantially increased the products spliting off of the water-insoluble of silanol particles aggregate. Photo labile silanol was possibly useful for coatings applications. It is also indicated that the cleaved surfactants bearing a siloxane as the functional group of water repellency effect for nylon fabrics are referred to as functional surfactants.