Method for synthesizing natural melanin-based resin through free radical polymerization

The invention specifically relates to a method for synthesizing natural melanin-based resin through free radical polymerization, belonging to the technical field of preparation methods for bio-based resin. The method comprises the following steps: putting natural melanin into a reactor; preparing a natural melanin solution by using a basic solvent; then adding persulfate as a free radical inducing agent, carrying out free radical polymerization at a temperature in a range of room temperature to 100 DEG C for 10 min to 7 d; separating a crude natural melanin-based resin product from a reaction system through centrifugation or filtering; and carrying out repeated washing so as to obtain the finished natural melanin-based resin. The synthetic resin provided by the invention uses widely available raw materials and has good environmental compatibility; the prepared resin is an insoluble gel or block or particle, does not need curing and leaves a small amount of residual monomers, and can be directly used after drying or used as matrix resin for a composite material; a reaction system is simple; reaction process is mild, stable and low in energy consumption; and the method is low in production cost, high in efficiency and beneficial for industrial production.