The role of the molecular organization of oligomers in the process of linear polyurethane formation

Effect of the molecular organization of oligomers on the kinetics of urethane formation and the molecular characteristics of the products was studied for the interaction of 2,4-toluylene diisocyanate with oligobutadienediols of various molecular masses. It is shown that the kinetic parameters of reactions in the case of single- and two-stage synthesis are determined by changes in the ratio of the types of associated hydroxyl groups both in the initial oligobutadienediols (autoassociated and π-bound) and in the course of reaction (autoassociated and π-bound groups and associates of the hydroxyl and urethane groups). Possible reasons for inversion of the dependence of the ratio of constants for the sequential process stages on the molecular mass of the oligomer are considered on the basis of notions of the structure of solution and associates.