The story on intrinsic (bio)degradability is completely different upon dealing with polymers bearing heteroatoms in the backbones or main chains, such as polyesters, polythioesters, polyoxazolines, and poly(phosphoester)s, as made from polycondensation and ring-opening polymerization routes. These synthesis routes are unfortunately more restrictive than radical (chain-growth) polymerization routes, and the range of polymers that can be prepared is smaller, inhibiting to easily obtain polymer materials combining degradability upon demand and key properties of traditional vinyl polymers (e.g. a high tensile and impact strength).