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Feature: The polymerization mechanism of styrene-butadiene resin is typical anionic polymerization, and the process used is solution polymerization. The characteristics of anionic polymerization can be summarized as: rapid initiation, slow growth, no transfer, and no termination. In more detail, under appropriate conditions, chain transfer and termination can occur; theoretically, the chain growth reaction can proceed indefinitely until all the monomers in the solvent have reacted to form polymers, with no monomers remaining in the system. The conversion rate of the polymerized monomers can easily reach or approach 100%. Other characteristics of this reaction are as follows: for monomers with conjugated systems, color changes often occur during the polymerization process, and these changes can be used to determine whether the polymerization is proceeding normally. The presence of benzene rings or heterocycles leads to a conjugation effect that causes the solution to appear red; whereas the C-anions formed from conjugated dienes lack a sufficient conjugation system, so the solution remains colorless. However, when polar solvents and additives are present in the system, these polar substances complex with anions, causing the solution to turn red. Polymer chains that remain active are called active polymers (polymer design or tailor-made).