A series of polyethers was prepared by monomer-activated anionic polymerization. The combination of an ammonium salt with triisobutylaluminum allowed the polymerization of epoxides containing various aliphatic side chains (1,2-butene oxide (BO), 1,2-hexene oxide (HO), and 1,2-octadecene oxide (ODO)) or a fluorinated group (3,3,3-trifluoro-1,2-epoxypropane (TFEP)). Polymers of molar masses up to 35 000 g/mol with relatively narrow molar mass distribution could be synthesized. Polymer structures were analyzed by C-13 NMR, and the thermal behavior was studied by differential scanning calorimetry (DSC). The evolution of hydrophobicity was investigated according to the length and composition of the side chain. Using a long aliphatic side-chain epoxide (C16) imparted crystallinity to the resulting atactic polymer.