The optimal ratio of diisocyanate to polyol for synthesizing polyurethane with the desired mechanical properties depends on the specific application and desired properties of the final product. In general, the ratio is determined by the stoichiometry of the reaction between the diisocyanate and the polyol.A 1:1 molar ratio of diisocyanate to polyol is typically used as a starting point for synthesizing polyurethane. However, this ratio can be adjusted to achieve specific properties in the final product. For example, increasing the diisocyanate content can result in a more rigid and stronger polyurethane, while increasing the polyol content can lead to a more flexible and softer material.It is important to consider the molecular weights of the diisocyanate and polyol, as well as the functionality of the polyol i.e., the number of reactive hydroxyl groups per molecule when determining the optimal ratio. Additionally, other factors such as the presence of catalysts, chain extenders, and additives can also influence the mechanical properties of the final polyurethane product.In summary, the optimal ratio of diisocyanate to polyol for synthesizing polyurethane with the desired mechanical properties will depend on the specific application and desired properties, and may require some experimentation to fine-tune the formulation.