Thermosetting polymeric compositions, such as polyurethane compositions, and related methods are provided. The invention relates to coating and polymer compositions and related methods derived from a biodegradable natural polysaccharide compound such as chitosan, pectin, heparin, and combinations thereof reacted to a cyclic oxide compound, such as an oxetane, oxolane or oxepane compound. The compositions and methods of the present invention exhibit self-repairing properties upon exposure to ultraviolet (UV) light. The compositions and methods of the present invention can be used in many coating applications, such as the transportation, packaging, fashion, and biomedical industries.