Free-radical synthesis of block copolymers on an industrial scale

Controlled free‐radical polymerization has been monitored with great interest in recent years since it offers an opportunity to combine the advantages of conventional free‐radical polymerization with those of living ionic polymerization. We present the 1,1‐diphenylethene (DPE) method which enables us to produce block copolymers on an industrial scale by a free‐radical mechanism. This DPE process enables industrially relevant monomers, such as styrene, methacrylates, acrylates, methacrylic acid, acrylic acid and N‐vinyl compounds, to be converted into block copolymers. The synthesis can be carried out in organic solvents, without solvents or in water. We have been able to demonstrate, that the addition of 1,1‐diphenylethylene to a normal free‐radical polymerization results in polymers whose molar mass, after a short uncontrolled phase, increases in a linear manner with conversion. The amount of 1,1‐diphenylethylene added also determines the order of magnitude of the final molar mass. It was also possible to employ the polymers isolated during this polymerization as initiators for the polymerization of a further monomer, resulting in the formation of block copolymers. With possibly somewhat reduced claims on the perfection of the structures, a wide variety of possibilities arise with the known advantages of free‐radical polymerization. The one‐pot synthesis is carried out by simple successive addition of the desired monomers and has already been used successfully on an industrially relevant scale.