Closed-System One-Pot Block Copolymerization by Temperature-Modulated Monomer Segregation

A biphasic one‐pot polymerization method enables the preparation of block copolymers from monomers with similar and competitive reactivities without the addition of external materials. AB diblock copolymers were prepared by encapsulating a frozen solution of monomer B on the bottom of a reaction vessel, while the solution polymerization of monomer A was conducted in a liquid layer above. Physical separation between the solid and liquid phases permitted only homopolymerization of monomer A until heating above the melting point of the lower phase, which released monomer B, allowing the addition of the second block to occur. The triggered release of monomer B allowed for chain extension without additional deoxygenation steps or exogenous monomer addition. A method for the closed (i.e., without addition of external reagents) one‐pot synthesis of block copolymers with conventional glassware using straightforward experimental techniques has thus been developed. Keep it cool is the rule: AB diblock copolymers were prepared by conducting the solution polymerization of monomer A in a liquid layer above a frozen solution of monomer B. When the vessel is heated to above the melting point of the lower phase, monomer B is released, and the desired block copolymers are obtained.