Non-silicone, urethane-based adhesives are disclosed which are prepared by the polymerization of reactive oligomers with the general formula X-A-B-A-X, where X is an ethylenically unsaturated group B is a unit free of silicone, and A is a urethane linkage. The adhesives are optically clear, self wetting and removable. Adhesive articles, including optical adhesive articles, may be prepared using the disclosed non-silicone urethane-based adhesives.