In one aspect, urethane waxes are described herein comprising a reaction product between monofunctional polyethylene oxide and polyisocyanate. In some embodiments, the urethane waxes are combined with other components to provide support materials for use in three-dimensional printing applications. A support material ink, for example, comprises a urethane wax comprising a reaction product between monofunctional polyethylene oxide and polyisocyanate. The support material ink, in some embodiments, further comprises monomeric curable material, oligomeric curable material, or mixtures thereof.