Meanwhile, the reactive difference between the isocyanate groups is decreased by elevated reaction temperature . As a result, a mixture of products will be obtained either with one dominant monomer or several monomers. Thus, the choice of the appropriate catalyst has significant impact on obtained product properties. In our work, a magnesium-titanium (IV) butoxide catalyst was selected due to its effect on increasing reactivity of the secondary NCO of IPDI. Selective reaction of the alicyclic NCO with hydroxyl group of P1838 and the aliphatic NCO with hydroxyl of HEMA, in the first and second steps of the process, respectively, led to the product with the one predominant macromonomer (Figure ).