The optimal ratio of diisocyanate and polyol for synthesizing polyurethane with maximum mechanical strength and thermal stability depends on the specific types of diisocyanate and polyol being used, as well as the desired properties of the final product. In general, a stoichiometric ratio of 1:1 one diisocyanate molecule to one polyol molecule is used to ensure complete reaction and formation of the urethane linkage.However, this ratio can be adjusted depending on the desired properties of the final polyurethane product. For example, increasing the diisocyanate content can lead to a more rigid and thermally stable polyurethane, while increasing the polyol content can result in a more flexible and elastomeric material.It is essential to consider the specific application and desired properties of the polyurethane when determining the optimal ratio of diisocyanate and polyol. In some cases, additional components such as chain extenders, crosslinkers, or catalysts may also be used to further tailor the properties of the final product.