The optimum temperature and ratio of reactants for the synthesis of polyacrylonitrile PAN from acrylonitrile monomer using free-radical polymerization can vary depending on the specific reaction conditions and the desired properties of the final product. However, some general guidelines can be provided.Temperature: Free-radical polymerization of acrylonitrile is typically carried out at temperatures between 40C and 70C. Lower temperatures can result in slower reaction rates, while higher temperatures can lead to increased side reactions and degradation of the polymer. The optimum temperature for maximum yield may vary depending on the specific initiator and reaction conditions used, but it is generally found within this range.Ratio of reactants: The ratio of reactants in a free-radical polymerization reaction typically refers to the ratio of monomer to initiator. The optimal ratio can depend on the specific initiator used and the desired molecular weight of the resulting polymer. In general, a higher monomer-to-initiator ratio will result in a higher molecular weight polymer, while a lower ratio will result in a lower molecular weight polymer. For the synthesis of PAN, a monomer-to-initiator ratio of around 100:1 to 500:1 is commonly used. However, the exact ratio should be determined based on the specific initiator and reaction conditions employed.It is important to note that achieving maximum yield in the synthesis of PAN may also depend on other factors, such as the choice of solvent, the presence of chain transfer agents, and the reaction time. Additionally, the optimal conditions for maximum yield may not necessarily result in the desired properties for the final polymer, so it is essential to consider the specific application and requirements of the PAN product when determining the best reaction conditions.