Polyacrylonitrile PAN is synthesized from acrylonitrile monomer through a process called free radical polymerization. To achieve optimum reaction conditions for synthesizing PAN, several factors need to be considered:1. Temperature: The polymerization of acrylonitrile is an exothermic reaction, meaning it releases heat. The optimum temperature for the reaction is typically in the range of 50-70C. Higher temperatures can lead to side reactions and degradation of the polymer, while lower temperatures may result in slow reaction rates and incomplete polymerization.2. Initiator: A suitable initiator is required to start the free radical polymerization process. Common initiators for acrylonitrile polymerization include azo compounds e.g., azobisisobutyronitrile, AIBN and peroxides e.g., benzoyl peroxide . The initiator concentration should be optimized to achieve a balance between reaction rate and polymer molecular weight.3. Solvent: The choice of solvent can significantly impact the polymerization process. Solvents should be chosen based on their ability to dissolve both the monomer and the polymer, as well as their compatibility with the initiator. Common solvents for acrylonitrile polymerization include water, dimethylformamide DMF , and dimethyl sulfoxide DMSO .4. Inhibitor: Acrylonitrile is prone to spontaneous polymerization, so an inhibitor is usually added to the monomer to prevent this. Typical inhibitors include hydroquinone, methyl ether of hydroquinone MEHQ , and phenothiazine. The inhibitor should be removed or neutralized before initiating the polymerization reaction.5. Reaction time: The reaction time should be optimized to achieve the desired degree of polymerization and molecular weight. Longer reaction times can lead to higher molecular weight polymers, but may also result in increased side reactions and degradation.6. Stirring: Proper mixing is essential to ensure uniform polymerization and prevent localized overheating. Adequate stirring should be maintained throughout the reaction.7. Post-polymerization treatment: After the polymerization is complete, the PAN may need to be purified by removing unreacted monomer, solvent, and any impurities. This can be achieved through processes such as precipitation, washing, and drying.In summary, the optimum reaction conditions for synthesizing polyacrylonitrile from acrylonitrile monomer involve carefully controlling the temperature, initiator, solvent, inhibitor, reaction time, and stirring. Additionally, post-polymerization treatment may be necessary to obtain a high-quality PAN product.