The optimal reaction conditions for synthesizing high molecular weight polyacrylonitrile PAN from acrylonitrile monomer with maximum yield and purity are as follows:1. Temperature: The optimal temperature for PAN synthesis is typically in the range of 60-70C. This temperature range allows for a controlled polymerization rate, ensuring a high molecular weight product without causing premature termination or side reactions.2. Pressure: The polymerization of acrylonitrile is usually carried out under atmospheric pressure. However, if the reaction is performed in a closed system, a slight positive pressure e.g., 1-2 bar can be applied to prevent the ingress of air and moisture, which could lead to impurities in the final product.3. Catalyst: The most common catalysts used for the synthesis of PAN are redox initiators, such as ammonium persulfate APS and sodium metabisulfite SMBS . The optimal catalyst concentration depends on the desired molecular weight and reaction rate, but typically falls in the range of 0.1-1.0 wt% relative to the monomer.4. Reaction time: The reaction time for PAN synthesis depends on the desired molecular weight and reaction conditions. Generally, higher molecular weight PAN requires longer reaction times. For a high molecular weight PAN, the reaction time can range from several hours to a couple of days. It is essential to monitor the reaction progress by analyzing the molecular weight and conversion of the polymer at regular intervals.5. Solvent: The polymerization of acrylonitrile is often carried out in an aqueous medium, as water-soluble initiators can be used, and the heat generated during the reaction can be easily dissipated. However, other solvents, such as dimethyl sulfoxide DMSO or dimethylformamide DMF , can also be used to control the reaction rate and achieve higher molecular weights.6. Inhibitors: To prevent premature polymerization and ensure maximum yield and purity, inhibitors such as hydroquinone or methyl hydroquinone can be added to the reaction mixture at a concentration of around 10-50 ppm.In summary, the optimal reaction conditions for synthesizing high molecular weight PAN from acrylonitrile monomer with maximum yield and purity involve a temperature of 60-70C, atmospheric pressure, redox initiators as catalysts, reaction times ranging from several hours to a couple of days, and the use of appropriate solvents and inhibitors.