Nonionic oligomeric surfactants and their use as dispersants and stabilisers

A hydrophobically capped oligomeric acrylamide or pyrrolidone is employed as a dispersant for hydrophobic materials in an aqueous medium containing a hydrophilic colloid, e.g. gelatin. The hydrophobic materials include photographic addenda such as colour couplers or solid particle dyes. Preferred dispersants have the general formula R-L-T or in which R, R and R are each independently selected from aliphatic hydrocarbyl, aryl(aliphatic hydrocarbyl) and (aliphatic hydrocarbyl)-aryl groups, L is a sulphur atom or a linking group that contains a sulphur atom attached to the T group, and T is a hydrophilic oligomeric group obtained by the oligomerisation of one or more vinyl monomers having an amido function.