We performed the studies on the use of oligodiurethane diisocyanates as an additive to a solution of triacetate cellulose polymer. It was shown that these compounds are effective additives and can be used as structural plasticizers of supramolecular formations of triacetate cellulose (in small quantities of 0.01–0.075 wt.% with respect to the weight of triacetate cellulose), which allows adjusting the viscosity of the solution at the stage of casting films in a wide range. In addition, the investigated compounds are effective modifiers of the properties of the obtained film materials (they approximately double the tensile strength of films, their relative elongation and relative hardness). The improvement in physical-mechanical properties of the test film samples is due to the presence of polar urethane groups in the structure of the additive, which are characterized by higher values of total volumetric energy of cohesive interaction than those of phthalate or adipinate oligomers known as plasticizers.