The optimal ratio of diisocyanate and polyol in the synthesis of polyurethane to achieve the desired mechanical properties and durability of the resulting material depends on the specific application and desired properties of the end product. In general, a 1:1 molar ratio of diisocyanate to polyol is used to ensure complete reaction and formation of the polyurethane polymer.However, this ratio can be adjusted depending on the desired properties of the final product. For example, increasing the diisocyanate content can result in a more rigid and durable material, while increasing the polyol content can lead to a more flexible and softer material.It is important to consider the specific diisocyanate and polyol types being used, as well as any additives or catalysts that may be included in the formulation. Ultimately, the optimal ratio will depend on the specific requirements of the application and may require experimentation and testing to determine the best balance of properties.