The correct option for the synthesis of addition polymers is **C. Chain-growth polymerization**. ### Detailed Explanation **1. Understanding Addition Polymers:** Addition polymers are formed by the addition of monomer units that contain a double bond (usually carbon-carbon double bonds, C=C). During the polymerization process, these double bonds are broken, allowing the monomers to link together into long chains. **2. Chain-Growth Polymerization:** Chain-growth polymerization is a method specifically designed for the synthesis of addition polymers. In this process, the polymer grows by the successive addition of monomer units to an active site on a growing polymer chain. This active site can be a free radical, cation, or anion, depending on the type of chain-growth polymerization being used. - **Initiation:** The process begins with the generation of active species (free radicals, cations, or anions) that can react with the monomer. - **Propagation:** The active species reacts with the monomer, forming a new active site that can react with another monomer, continuing the chain growth. - **Termination:** The process ends when two active chains combine or when an active chain reacts with a terminating agent. **3. Why Other Options Are Incorrect:** - **A. Condensation Polymerization:** - This method involves the reaction of monomers with two functional groups, leading to the elimination of a small molecule (like water or methanol) during the polymerization process. It is not used for addition polymers, which do not involve the loss of small molecules. Instead, condensation polymers are typically formed from monomers that contain two or more reactive functional groups (e.g., diols and dicarboxylic acids). - **B. Ionic Polymerization:** - While ionic polymerization can be a method for synthesizing addition polymers, it is a specific type of chain-growth polymerization. It involves the use of ionic species (cations or anions) to initiate the polymerization. However, the term "chain-growth polymerization" encompasses both ionic and radical mechanisms, making it a broader and more accurate choice for the question. - **D. Step-Growth Polymerization:** - This method involves the reaction of monomers with two or more functional groups, similar to condensation polymerization. In step-growth polymerization, any two molecular species can react, regardless of their size, leading to the formation of oligomers and eventually long-chain polymers. This method is not specific to addition polymers and is more commonly associated with the formation of polyesters and polyamides. ### Summary of Key Points - **Addition polymers** are formed by the addition of monomers with double bonds. - **Chain-growth polymerization** is the correct method for synthesizing addition polymers, involving initiation, propagation, and termination steps. - **Condensation polymerization** and **step-growth polymerization** do not apply to addition polymers as they involve the loss of small molecules or reactions between functional groups. - **Ionic polymerization** is a subset of chain-growth polymerization but is not as general as the term "chain-growth polymerization." ### Revision Summary - Addition polymers are synthesized through chain-growth polymerization. - Chain-growth polymerization involves initiation, propagation, and termination. - Condensation and step-growth polymerization do not apply to addition polymers. - Ionic polymerization is a specific type of chain-growth polymerization.