The synthesis of high molecular weight polyvinyl alcohol PVA from vinyl acetate monomer VAM typically involves two main steps: polymerization of VAM to polyvinyl acetate PVAc and hydrolysis of PVAc to PVA.1. Polymerization of VAM to PVAc:The optimal catalyst for this reaction is a free-radical initiator, such as azobisisobutyronitrile AIBN or benzoyl peroxide. The reaction conditions for the polymerization are as follows:- Temperature: 60-80C- Pressure: Atmospheric pressure- Solvent: A suitable solvent like methanol or ethanol can be used to control the reaction rate and molecular weight.- Reaction time: 6-24 hours, depending on the desired molecular weight of PVAc.2. Hydrolysis of PVAc to PVA:The optimal catalyst for this reaction is an alkaline catalyst, such as sodium hydroxide NaOH or potassium hydroxide KOH . The reaction conditions for the hydrolysis are as follows:- Temperature: 60-90C- Pressure: Atmospheric pressure- Solvent: Water is used as a solvent in this step.- Reaction time: 1-5 hours, depending on the desired degree of hydrolysis.To obtain high molecular weight PVA, it is essential to control the reaction conditions, such as temperature, reaction time, and concentration of the catalyst. Lower temperatures and longer reaction times can help achieve higher molecular weights. Additionally, the choice of solvent and the concentration of the catalyst can also influence the molecular weight of the resulting PVA.