The ability to tailor polymers and additives for various performance needs may get a boost from a new product designed to give materials producers greater control over the molecular structures and properties of their grades. BlocBuilder, from chemical company Arkema Inc. of Philadelphia, is a nitroxide-based compound with alkoxyamine that combines a free-radical polymerization controller and free-radical initiator in one molecule, enabling formulators to achieve precise molecular weights and exact copolymer sequencing in resins and additives.