The synthesis of polystyrene from styrene monomer typically occurs through a process called free radical polymerization. Here is the step-by-step mechanism:1. Initiation: A free radical initiator, such as benzoyl peroxide or azobisisobutyronitrile AIBN , is added to the styrene monomer. The initiator undergoes homolytic cleavage, producing two free radicals. These radicals are highly reactive and can initiate the polymerization process by attacking the double bond in the styrene monomer.2. Propagation: The free radical generated in the initiation step reacts with the styrene monomer, forming a new radical on the styrene molecule. This new radical can then react with another styrene monomer, adding it to the growing polymer chain. This process continues, with the polymer chain growing in a stepwise manner as more and more styrene monomers are added.3. Termination: The polymerization process can be terminated through several mechanisms, including coupling two growing polymer chains react with each other , disproportionation a hydrogen atom is transferred from one radical to another, forming a double bond , or by reaction with a chain transfer agent a molecule that reacts with the growing polymer chain to form a new radical, effectively stopping the growth of the original chain . Termination results in the formation of the final polystyrene polymer.Key factors that affect the yield and quality of the final product include:1. Temperature: The reaction rate and the molecular weight of the final polymer are influenced by temperature. Higher temperatures increase the rate of initiation and propagation, but also increase the rate of termination, which can lead to lower molecular weight polymers.2. Concentration of initiator: The concentration of the initiator affects the number of polymer chains formed and the molecular weight of the final product. Higher initiator concentrations result in more polymer chains with lower molecular weights, while lower initiator concentrations result in fewer chains with higher molecular weights.3. Reaction time: The longer the reaction time, the higher the conversion of styrene monomers to polystyrene. However, extended reaction times can also lead to side reactions and degradation of the polymer.4. Impurities: Impurities in the styrene monomer or initiator can interfere with the polymerization process, leading to lower yields and poor-quality polystyrene.5. Polymerization conditions: The choice of solvent, pressure, and other reaction conditions can also affect the yield and quality of the final product. For example, the use of a solvent can help control the viscosity of the reaction mixture and improve heat transfer, leading to better control over the polymerization process.By carefully controlling these factors, it is possible to optimize the synthesis of polystyrene from styrene monomer and obtain a high-quality final product.