William Neal Fenton

The addition of polyoxyethylene/polyoxypropylene block copolymers to silicone surfactant systems to improve the porosity of flexible polyurethane foam

ilicone surfactants are used for the production of flexible polyurethane foam. These surfactants are commonly graft copolymers of polydimethylsiloxane (silicone) and various polyethers containing ethylene oxide and propylene oxide monomeric units. A typical structure of these copolymers is shown in Figure 1. This structure allows the copolymer to favorably orient itself at the bubble surface. The siloxane backbone is believed to reside on the air side of this interface while the polyether chains extend into the polyurethane matrix. The role of the silicone surfactant in the production of these foams appears to be complex and quite controversial. Its role in the reduction of the surface tension of the liquid mixture of polyoxypropylene glycols, toluene diisocyanates, and various additives [catalysts, blowing agent (usually methylene chloride), water] has been well documented [1-3].