A range of hydrophilic poly(methyl vinyl ether) (PMVE) polymers was synthesized by living cationic polymerization of methyl vinyl ether (MVE), having different hydrophilic or hydrophobic chain-end functionalities. The dissimilar end-groups were either introduced by end-capping of the growing polymer chain with LiBH4, methanol, and water or by functional initiation with 2-bromo-(3,3-diethoxy-propyl)-2-methylpropanoate. The synthesized PMVEs were characterized by H-1 NMR, size exclusion chromatography, and matrix-assisted laser desorption ionization time of flight, displaying a narrow polydispersity. Modulated temperature DSC was applied to study the influence of the nature of the end-groups on the solubility behavior of PMVE in water. Terminal-modification with a hydroxyl function improves the solubility, whereas a Br-containing end-group causes the polymer to be insoluble in water at room temperature; however, the special type III lower critical solution temperature demixing behavior being maintained. (c) 2005 Wiley Periodicals, Inc.