To optimize the synthesis of polyacrylonitrile PAN and increase its yield and purity using acrylonitrile AN monomer as the primary starting material, several factors should be considered:1. Choice of initiator: Select an appropriate initiator that can efficiently initiate the polymerization of acrylonitrile. Common initiators for PAN synthesis include redox initiators e.g., ammonium persulfate/sodium metabisulfite and azo initiators e.g., azobisisobutyronitrile, AIBN . The choice of initiator can significantly affect the reaction rate, molecular weight, and purity of the resulting polymer.2. Reaction temperature: The polymerization temperature should be carefully controlled to balance the reaction rate and the stability of the initiator. Higher temperatures can lead to faster reaction rates but may also cause premature initiator decomposition, leading to lower molecular weight PAN. Optimal temperatures for PAN synthesis typically range from 40 to 70C, depending on the initiator used.3. Monomer concentration: The concentration of acrylonitrile in the reaction mixture can affect the polymerization rate and the final molecular weight of PAN. Higher monomer concentrations can lead to higher reaction rates and molecular weights, but may also result in increased viscosity and difficulty in mixing. Optimal monomer concentrations should be determined experimentally for the specific reaction conditions used.4. Reaction time: The polymerization reaction should be allowed to proceed for a sufficient amount of time to achieve high conversion of the monomer to the polymer. However, excessively long reaction times can lead to side reactions and impurities in the final product. Monitoring the reaction progress e.g., by measuring the viscosity or conversion can help determine the optimal reaction time.5. Purification: After the polymerization is complete, the PAN product should be purified to remove any unreacted monomer, initiator residues, and other impurities. Common purification methods include precipitation in a non-solvent e.g., methanol or water , followed by filtration and washing. The purified PAN can then be dried under vacuum to remove any residual solvent.6. Copolymerization: To improve the properties of PAN, it can be copolymerized with other monomers, such as methyl acrylate or itaconic acid. The choice of comonomer and its concentration can significantly affect the properties of the resulting copolymer, such as its solubility, thermal stability, and mechanical properties. The copolymerization conditions should be optimized to achieve the desired balance of properties.By carefully considering these factors and optimizing the reaction conditions, it is possible to increase the yield and purity of polyacrylonitrile synthesized from acrylonitrile monomer.