Monoethylenically unsaturated polymerizable monomers carrying a plurality of ketimine-blocked primary amine groups are disclosed. These are preferably provided by reacting an organic diisocyanate with the single secondary amine group of a ketimine-blocked diprimary amine carrying a single secondary amino hydrogen atom and then reacting a monohydric acrylate with the other isocyanate group. These monomers are polymerizable to provide copolymers with other monoethylenically unsaturated monomers, and especially acrylate-functional monomers, in which the amine groups remain blocked. These amine groups become unblocked when the copolymers are dispersed in water to form various types of aqueous coating compositions.