The mechanism of anionic catalyzed ring opening polymerization of cyclic siloxanes is: strong base anions attack silicon atoms to undergo nucleophilic reactions=>forming anionic reaction active centers (slow); Anionic active centers trigger ring opening polymerization of cyclic siloxanes=>chain growth reaction (fast); Chain transfer and chain termination reactions occur between the active center and the capping agent; On the other hand, while the active centers of macromolecules undergo chain growth reactions, they also undergo nucleophilic reactions within the molecule, known as back biting reactions or reverse closed-loop degradation reactions. Therefore, anionic ring opening polymerization is an equilibrium reaction. The open-loop reaction rate is usually between 84-88%, so the reaction still requires high-temperature vacuum extraction to remove~14% of the ring.

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