A family of oligomers consisting of poly(oxyethylene) (POE) blocks and secondary amine and phenol functionalities were prepared from the Mannich reaction of alkylphenols, formaldehyde, and POE-diamines. The Mannich oligomers were characterized by amine titration, GPC, H-1 NMR, DSC, and TGA. In aqueous solution, the Mannich amines behaved as nonionic surfactants, exhibiting properties such as inverse temperature solubility behavior (between 24 degreesC and 39 degreesC), phase changes versus concentrations, surface tension reduction, and self-aggregation into particles mostly ranging from 20 to 1400 nm in diameter. The amphipathic balance in the structure, concentration, and pH influenced the self-aggregating size. The H-1 NMR integration further revealed that these aggregates could undergo phase inversions in different solvent environments. (C) 2003 Elsevier Science (USA). All rights reserved.