Methods of treating fibers comprising a polymer including at least one of a vinyl acetate moiety or a vinyl alcohol moiety, and resulting fibers or the products comprising the resulting fibers are disclosed. In an example embodiment, a fiber having a surface region and an interior region, includes a polymer comprising at least one of a vinyl acetate moiety or a vinyl alcohol moiety chemically modified with a modification agent. The fiber has a transverse cross-section including the interior region comprising the polymer having a first degree of modification and the surface region comprising the polymer having a second degree of modification greater than the first degree of modification.