ИСТИНА

Poly (siloxane urethanes) are copolymers, as a rule, of a polyblock structure, in which special properties characteristic for each of the components are combined: mechanical strength and wear resistance of polyurethanes with thermo-, frost and hydrolytic resistance of polysiloxanes. In the work, poly (buthylene oxide siloxane urethanes) (PBOSU) based on oligo (buthylene oxides) and oligo (dimethyl siloxane diols) with –CH2O(CH2)2OH end groups have been synthesized. Synthesis of the copolymers was carried out in solution and in bulk. In both methods, prepolymers with terminal –NCO groups, 2,4-toluene diisocyanate, and aromatic diamines as cross-linking agents were used. When synthesized in solution (MEK), the reaction proceeds at room temperature, without a catalyst and a chain extender and follows by heating the film at 100 °C to complete the crosslinking process. All PBOSUs have high deformation-strength characteristics: the tensile strength-at-break reaches 58 MPa, and the elongation at break of individual samples is 1000%. It should be noted, the strength of the films decreases with increasing MM and the mass content of the siloxane blocks. There is also a decrease in the modulus of elasticity G' due to a decrease in the concentration of hydrogen bonds. It agrees well with the data of IR spectroscopy. The glass transition temperature of PBOSUs depends on MM of oligo (siloxane diols) and the component ratio. If the threshold temperature of the decomposition does not depend on the content of siloxane blocks for the samples obtained by one-step synthesis in solution developed by us, then for the PBOSU samples obtained without solvent the introduction of the siloxane blocks induces a slight increase in the thermal stability [1]. A preliminary assessment of the hemocompatibility of the organic polyurethane and PBOSUs of various compositions at the A.N. Bakulev National Medical Research Center for Cardiovascular Surgery has shown that these polymers are promising materials for further in vitro and in vivo studies. They might be applied in the development of artificial heart lobe valves, as well as in balloons for counterpulsation. It is important to note, the synthesis of copolymers takes place without catalysts (usually, organic tin compounds), which is essential for using materials that come in contact with blood.