Spontaneous synthesis of a homogeneous thermoresponsive polymer network composed of polymers with a narrow molecular weight distribution

We have developed a method to obtain a polymer gel consisting of a relatively homogeneous network structure composed of polymers with a narrow molecular weight simply by mixing the necessary compounds. In this method, a radical chain polymerization reaction with a fast reaction rate is combined with a radical addition cross-linking reaction that has a sufficiently slow reaction rate compared with the polymerization reaction. For the polymerization reaction, a multifunctional initiator with a strictly controlled number of polymerization initiation sites was used to prepare a star polymer with a chain number and length determined by living radical polymerization. In the cross-linking reaction, a multifunctional terminating agent was used to prepare a star polymer from a polymer with a narrow molecular weight via living radical polymerization followed by coupling with multiple polymer chains using a termination reaction. As a result, two kinds of reactions with greatly different kinetics occurred sequentially only when all of the compounds were mixed and allowed to stand at a constant temperature, and a relatively homogeneous network structure comprising cross-linked polymers with a low molecular weight distribution was inherently constructed.