Sequential three-component polyaddition has been difficult, because the first addition typically consumes the two reactive monomers to produce a stable intermediate that cannot react smoothly with the remaining most stable monomer. The combination of nucleophilic and radical additions has overcome this thermodynamic problem. The first nucleophilic addition of diamines to cyclic dithiocarbonates produces bis(mercaptothiourethane)s that can attack diethynylbenzene radically, which consequently gives poly(thiourethane-phenylenevinylenesulfide)s in high atom efficiency up to 95%. The resulting polymer extracted palladium and gold cations from their aqueous solutions in excellent efficiencies.